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Chastity - A Guide for Teens and Young Adults

The Divine Plan of Reproduction

by Fr. Gerald Kelly

The ultimate meaning of sex is reproduction. Only when we see the full meaning of human parenthood do we realize why God created us man and woman, fashioned our bodies so differently, endowed each in a peculiar way with the psychic characteristics necessary for fatherhood or motherhood respectively, and gave that strong mutual attraction that was the subject of the first part of this series. God might have established a world in which He would create each human being entirely, body and soul. In that case there would be no reason for sex and its accompanying characteristics. We could all have the same kind of bodies, and the height of our companionship would be the simple friendship.

God established the present order of things. He established a system of reproduction that requires the cooperation of human parents; He has the child come into the world weak and helpless and needing the care of the parents for his continued existence; He has the child mature slowly, with a distinct need for the care of his parents for his mental and moral training. All this is God's plan for human reproduction and for the human development of the child. Sex was created as a means of accomplishing these ends. We have already seen, particularly in the study of personal sex attraction, how the two parents are united together in a lasting love-bond that provides for the education of the child. Now it will be well to consider more closely the factors involved in bringing the child into the world.

A newly-born baby is the product of the cooperation of three causes: God, nature, and the human parents, God creates the soul; the body is fashioned through the operation of certain very intricate and wonderful biological laws; and the parents place the one condition necessary in order that God and nature may accomplish their work. No code of sexual morality can be complete or reasonable which neglects any one of these causes; go as an essential part of the background required for the moral principles of chastity, we are including in this section of the series the fundamental ideas pertaining to each of these three factors of human reproduction.

God's Part

God's special part in the making of a human being is, obviously, the creation of the soul. This is not the place for a treatise on creation or on the soul, but it is the place to recall that this one divine operation makes human procreation totally different from the reproduction of brute animals. At the moment of conception the living thing in the body of the human mother, formed by the union of two almost infinitesimal germ cells, is a real human being with the rights of a human being and the dignity Of a human being, with an immortal soul, formed to the likeness Of God, destined to receive the supernatural life of Christ and to live eternally in union with the Blessed Trinity.

These are not mere glowing words; they express a sublime fact. It is absurd to speak of the science of human reproduction and to ignore the soul completely. One of the glaring faults of many modern booklets intended as sex instruction for the young is precisely is this: they treat the birth of a child like the birth of a kitten, and say absolutely nothing about the soul or its Creator. Such instruction is not Christian; in fact, it is not even human and it lays no foundation for true morality. To leave out the soul is to leave no place for chastity. Only when we consider the dignity of the child do we see the need and meaning of a moral code that provides for the proper use of the function by which that child is brought into the world. With the dignity of the soul in mind, we can see that chastity is not the mere suppression of a natural urge, but the guardian of a sacred power.

The creation of the soul is the work of God, and of God alone. He uses no created instrument, neither man nor angel. It is entirely His product. But in His infinite wisdom He has decreed that He will create the soul only when certain other conditions are fulfilled. These conditions must be fulfilled by nature and the human parents.

Nature's Part

The part played by nature and the human parents includes these three functions:

  1. The production of the father- and mother-cells. The mother-cell is scientifically termed the ovum, plural ova. The father-cell is termed spermatozoon, plural spermatozoa. More briefly, the father-cells are simply called the sperm.

  2. The transference of the father-cells to the body of the mother in such a way that they can migrate in search of an ovum.

  3. The union of the father- and mother-cells, and the subsequent development of the embryo and birth of the child.

Of these three functions, the second is the voluntary work of the parents, the first and third are involuntary processes of nature. These involuntary processes are described with technical accuracy in any good physiology book. There is no need of our recounting them here with the complete detail of the physiologist, but we do wish to sketch their essential features with this purpose in view: These functions, too, though not the exclusive work of God, as is the creation of the soul, are dependent on God, and do form a part of the divine scheme for human reproduction. In an ordinary physiological treatise this idea is not emphasized; in a moral treatise it is of supreme importance.


When a baby girl is born, she already possesses two tiny glands called ovaries. These are the principal glands distinctive of her sex. They are situated, one on each side, in the upper part of the pelvic cavity, which is located in the lower part of the abdomen. Even at birth they contain within themselves the beginnings of thousands of ova. As the child grows and matures, so do the ovaries grow and mature until at last they are about the size and shape of a large almond. With the age of puberty, the ova also begin to mature. But they reach their maturity slowly, only one at a time (except in rare cases), and at widely spaced intervals. When an ovum matures, the sac which contains it bursts, and it is discharged from the ovary. This phenomenon is called ovulation, the production of the mother-cell needed for procreation.

Puberty for girls in our country is usually between the ages of 12 and 14. Ovulation continues from this time until the change of life (the menopause), which usually occurs during the middle or late forties. During this entire time ovulation takes place with a certain rhythmic regularity. A rather ordinary period is one lunar month, 28 days, but this has many variations, both in length and regularity.

The principal glands distinctive of the sex of the boy are the testicles. These two glands are suspended between the thighs in a protective membranous pouch called the scrotum. In infancy they are quite small; when mature, they are somewhat larger than the ovaries, and oval-shaped. Each consists of a closely-compacted mass of tiny tubules in which the father-cells, are produced.

The production of the father-cells by the testicles is called spermatogenesis. This process, like ovulation, begins at puberty, which for boys in our country is usually between the ages of 13 and 16. A sperm is invisible to the naked eye; under the microscope it is seen to be shaped like a tadpole, with a head and a tail. Once the process of spermatogenesis begins, the spermatozoa are produced in great abundance and are stored in the testicles and also, according to some medical authorities, in the seminal vesicles, two glands within the abdominal cavity that are connected with the testicles by means of tubes called the seminal ducts.

There is no regular period for the discharge of the sperm cells as there is for the ova. The sperm cells can be kept for long periods of time, and they can be reabsorbed by the system. They do not have to be discharged, but it is a rather ordinary phenomenon that at varying periods the over-supply -will be discharged during sleep. In fact, this occurrence of seminal discharges during sleep is one of the usual signs of puberty in the boy. So long as it takes place during sleep, it should not be a source of worry, from either the physiological or moral point of view.

In the actual discharge of the sperm cells, many glands besides the testicles must cooperate. The tiny cells have a power of motion, but once they leave the testicles they must have some fluid in which to move. To aid their motion, nature supplies many other glandular secretions. A glance at the path taken by the sperm cells after they leave the testicles will indicate the position of these subordinate glands. One seminal duct leads from each testicle through the lower part of the abdominal cavity, crosses down behind the bladder, connects with a seminal vesicle (which we have already mentioned), and runs through a large chestnut-shaped gland called the prostate gland. Here the two ducts converge into one and enter the urethra, a canal which emerges from the abdominal wall through the penis, the male organ of copulation. Glandular secretions are added to the spermatic fluid by the seminal vesicles, the prostate gland, and several smaller glands adjacent to or within the urethra. These added secretions, besides giving the sperm cells a medium in which they can move freely, also serve to nourish them and to protect them by purifying the canal through which they pass.

Internal Secretions

Besides the production of the germ cells, the ovaries and testicles have another very important function. They belong to the series of glands known as the endocrine glands (internal secretion glands), called such because they pour their secretions directly into the blood stream and not into some duct which takes them outside the body. The secretions of the endocrine glands are chemical substances called hormones, which have a great deal to do with general physical wellbeing, with the growth and development of the body, and with emotional life. The ovaries and testicles secrete the sex hormones into the blood stream. These hormones are instrumental in the development of the physical changes characteristic of puberty, and their presence in the system also has considerable influence on the sexual appetite. For instance, an over-supply of sex hormones is frequently the basis for excessive sensitivity in regard to purity and also for prolonged and disturbing temptations.

Other Natural Processes

The production of the germ cells is the first of the involuntary natural processes pertaining to reproduction and goes on without any dependence on union of the sexes. The other natural processes can go on only after the father-cells have been transferred to the mother's body; hence sexual intercourse is their normal prerequisite. Granted that this parental work is performed, then nature can carry on the following functions:


When the matured ovum is discharged from the ovary, it usually enters an oviduct (Fallopian tube). There are two oviducts, each lying very close to an ovary in the pelvic cavity. In shape, the oviduct is like a tiny trumpet. Its outer and wider end drops down below the ovary, and it is made up of -any little fringes, the better to catch and hold the ovum. The smaller end of each oviduct leads into the womb (uterus). In shape and position, the womb resembles an inverted pear, the wider part on top and leaning forward in the pelvic cavity, the smaller part (the neck, or cervix) fitting snugly into the vagina, a canal which leads to the external organs of the female reproductive system. Ordinarily the womb measures about three inches from top to bottom and about three inches in diameter at its widest part. The vagina is usually about four inches in length.

When the ovum enters the oviduct, it begins immediately to travel toward the womb. It can live only a short time if it is not fertilized, so we may say truly that it is traveling in search of a sperm cell. The sperm is deposited within the vagina. From there it passes upward through the womb and enters the oviducts. In any single seminal discharge, there are millions of sperm cells, and each one is hunting for an ovum. But the first one to reach the ovum claims it as its prize. The head of the sperm enters the ovum, and the ovum then spontaneously closes against all other sperm cells. The only probability of a multiple entry occurs if two or more father-cells reach the ovum at exactly the same instant. The fusion of the nuclei of sperm and ovum is known as fertilization, or fecundation. This is the beginning of a new human life, and in all probability it is at this moment that God creates the soul. At least for all practical purposes we must regard the fertilized ovum, no matter how young and small, as the possessor of human life.


Every time ovulation occurs, a new endocrine gland called the corpus luteum is formed on the ovary. The corpus luteum is only a temporary gland; it does its work, and then disappears. But it performs a very important work. By means of its secretions it "superintends" all the elaborate preparations made for the reception of the fertilized ovum. These preparations mainly affect the womb. The womb is naturally an extraordinarily strong and muscular organ, capable of great expansion, and endowed with the richest of membranes. When the corpus luteum sends the message that the ovum is coming, the inner membranes of the womb are prepared in a special way to be a fit nesting place for the human embryo.

After the ovum is fertilized, it travels slowly through the oviduct, and after a journey of several days it enters the womb. It bores into the inner wall of the womb, generally in the upper part, and membranes begin to form about it. This process is known as Implantation.

(If it should happen that the ovum was not fertilized, then it can claim no nest in the womb. In fact, it is very likely dead long before it reaches the womb; hence all these preparations are useless, and the womb begins to contract and to expel the blood and glandular secretions that have gathered in the inner membranes. The expulsion of these materials is known as menstruation. Menstruation, like ovulation, begins with puberty--in fact, it is one of the perceptible signs of the advent of puberty in a girl. At first the menstrual periods are likely to occur rather irregularly, but after a time they usually attain a certain rhythmic frequency, as we mentioned in regard to ovulation. Menstruation lasts from two to five or six days. It is sometimes accompanied by a slight sickness, but not ordinarily by anything serious. Adolescent girls should be instructed by their mothers or by doctors as to the best way of caring for cleanliness and health during this time. It is a rather remarkable thing that some mothers say little or nothing to their daughters about menstruation and as a result some girls are thoroughly frightened by what should be taken as a perfectly natural physiological experience.)


Once the fertilized ovum has nested within the womb, it begins gradually to develop from its tiny embryonic state to that of a perfectly formed human child. This development usually takes about nine months. When the child in the womb has sufficiently developed, the membranes in which it is contained break away from the side of the womb and the child begins to descend. The small neck of the womb widens to almost unbelievable proportions, and the child passes through it into the vagina, thence through the outer maternal organs. All these processes imply great expansion of the organs, especially of the neck of the womb and of the vagina. This expansion is brought about by a series of powerful muscular contractions and generally to the accompaniment of great pain to the mother. But it is a temporary pain which is more than compensated for by the joy of motherhood.

The only part that the external female organs play in childbirth is to allow the passage of the child to the outside world. These organs (scientifically called the vulva) consist largely of spongy, muscular folds of tissue. Their main functions are to protect the precious inner organism by forming a sort of ante-chamber to the vagina and to aid in the accomplishment of the parental union required for fertilization.

The Finger of God

As we said at the beginning of this section on nature's part in procreation, we had no intention of giving a mere series of physiological facts. Our purpose is rather to call attention to the tremendous meaning underlying these facts. That meaning can be aptly expressed in one brief sentence: The finger of God is here. Note how the production of germ cells is delayed until the body begins to reach physical maturity and how the process of ovulation ceases at just the period in life when a woman would find the burden of future parenthood too great; note the remarkable growth of the tiny embryo from two cells, one of which is infinitesimal, the other just barely visible to the naked eye, to a fully formed baby; note the adaptability of the maternal organism as the embryo matures and the child is born. Add to these facts, the pathological endowments of the father and mother respectively, and no reasonable person can avoid the conclusion that this is a divine plan, that joking about it is tawdry and that interference with it is criminal.

The Parental Part

The hand of God is no less evident in the part that the human parents are destined to play in procreation. This consists in the voluntary act of sexual union, by which the father-cells are transmitted to the body of the mother in such a way that they can travel in search of an ovum. We have already considered the psychological background and significance of this act, also its spiritual and supernatural symbolism. These things are evidently designed by the Creator, and this same design is manifest in the purely physical aspect of parental intercourse. For it is God Who gives to each of us as potential parents, a generative faculty, God Who attaches to the use of that faculty a special physical pleasure, God Who has given a strong appetite for the enjoyment of that pleasure. A word about each of these three elements will not only indicate how they fit into the divine scheme, but will also serve as necessary background for the subsequent chapters of this series.

Generative Faculty

A faculty is a power of doing something; thus we speak of the faculty of speech, of hearing, of thought, and so forth. A faculty exercised through the body must have an organism apt for that purpose. Hence, the generative faculty consists, in the physical organism necessary and apt for carrying on the part in sexual union proper to one's particular sex. In both sexes this generative power resides largely in the external organs of reproduction. The womb and ovaries, for instance, are not needed for the parental act; their function belongs to the natural processes previously described.

Normally, the generative organs are in a relaxed condition and quite unfit for union. But God has so fashioned them that the necessary condition is easily induced. They consist of a highly sensitive nervous system, of blood vessels of a peculiar formation, of strongly contracting muscles, and of glands that secrete freely. When the nervous system is stimulated, blood flows freely into the organism and, because of the peculiar formation of the blood vessels, it cannot leave so long as the nerve stimulation is prolonged. Thus the organism distends and becomes firm and even more highly sensitive; the muscle begin to contract, and the glands to secrete. All of these processes, even the initial stimulations, form a part of the operation of the generative faculty, and are frequently styled the generative function. Evidently, the voluntary stimulation or promotion of any of them must be regulated according to God's law for the use of the generative faculty.


To the harmonious functioning of each of our natural faculties God has attached a definite pleasure. So, the processes of the generative function, once set in motion, are productive of extremely agreeable sensations. These sensations are particularly localized in the generative system, but as they, increase in vehemence they become a blinding passion influencing the entire personality. This pleasure is sometimes referred to as sensual, a misleading term, because it is often applied to sense pleasures which have nothing to do with sex. The most common theological name for this specific pleasure is venereal. This word has come to have an odious connotation because it is so often used in connection with disgusting diseases; yet for technical accuracy it is really the best of all terms. It is derived from an old Latin word meaning "pertaining to generation" (after Venus, goddess of generation), and for centuries it has been used by Catholic moral experts as the most unmistakable manner of classifying the pleasure attached to the generative function.

Still another term used to designate the pleasure attached to the use of the generative faculty is carnal--a word which indicates that this specific pleasure is experienced in a peculiar manner "in the flesh." Finally, an expression rather commonly used today as synonymous with venereal pleasure is sexual pleasure. This last is not in itself a most apt expression, as it could refer also to the joys of general and personal sex attraction, and these are not necessarily venereal. In the following pages, when we speak of sexual pleasure, sexual desire, or the sexual appetite, we are using the word in the physical sense (therefore as synonymous with venereal) unless a wider meaning is clearly indicated.


An appetite is simply a power for desiring or enjoying something. Almighty God has given all men some power of enjoying the use of their natural faculties, otherwise there would be grave danger that the purpose of these faculties would not be achieved. It is very difficult to eat, for instance, when sickness has blunted or taken away one's appetite. So in the sexual sphere, unless men were endowed with a sexual appetite, there would be grave danger that the propagation of the race would suffer.

When the sexual appetite is stimulated, it immediately contacts or, we might say, expresses itself through the nerves of the generative system and sets in motion the series of processes that we described as constituting the generative function. The principal stimulants to this appetite are kisses and embraces of an intimate or prolonged nature. Thinking on sexual matters also has the same effect, as also have many other things which influence the imagination, such as suggestive scenes in books, magazines, or motion pictures, the sight of a person who is physically attractive, dancing, and so forth. The fact that so many thing-, in life can and do influence the sexual appetite makes a clear knowledge of the meaning and obligations of chastity very important.

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