A number of other things remain to be said on this subject, but which I have treated of in the History of Man; however, before I entirely close, I shall make some few observations. The greatest part of animals do not seek for copulation until they are nearly arrived at their full growth; those which have only a particular season in the year have only seminal liquor at that time. A very capable observer of Nature[BK] not only saw this liquor forming in the roe of a Calmar, but even observed the spermatic animals and the roe itself, which have no existence till the month of October, the time when the Calmar spawns on the coast of Portugal, where Mr. Needham made these observations. As soon as the season is over neither seminal liquor nor spermatic animals are longer seen in the milt, which then dries up and becomes imperceptible till the season returns in the succeeding year, when the superfluous nutriment renews the milt, and fills it as before. In the history of the stag we have an opportunity of remarking on the different effects of rutting; the most general is, the increased size of the animal; and in those kinds of animals whose rutting or spawning is only made at great intervals, the extenuation of the body is proportionably great.
[BK] Mr. Needham's New Microscopical Discoveries, London, 1745.
As women are smaller and weaker than men, of a more delicate temperament, and eat much less, it is natural to imagine that their superfluous organic particles are not so plentiful; from hence their seminal liquor will be weaker, and less in quantity, than that of men. Since, likewise, the seminal liquor of females contains fewer organic particles than that of males, must there not result a greater number of males than females from the mixture of these two liquors? This is really the case, for which it has hitherto been thought impossible to find a reason. About a sixteenth more male children are born than females; and we find that the same cause produces the same effect in all kinds of animals on which we have been able to make this observation.
EXPOSITION OF THE SYSTEMS IN GENERATION.
Plato[BL] not only explains the generation of man, animals, plants, and elements, but even that of heaven and the gods, by reflected representations and images extracted from the Divine Creator, which, by an harmonic motion, are ranged according to the properties of numbers in the most perfect order. The universe, according to him, is a copy of the Deity: time, space, motion, and matter, are images of his attributes; and secondary and particular causes are results of numerical and harmonical qualities of those representations. The world is the most perfect being, and to have a complete perfection it was necessary that it contained every other animal, every possible representation, and every imaginable form, of the creative faculty. The essence of all generation consists in the unity and harmony of the number Three, or of the triangle, viz. that which generates, that in which generation is performed, and that which is engendered. The succession of individuals in the species is only a fugitive image of the immutable eternity of this triangular harmony, the universal prototype of every existence and every generation; for this reason two individuals are required to produce a third, and it is this which constitutes the essential order of father, mother, and child.
[BL] See the Timæus.
This philosopher is a painter only of ideas; disengaged from matter he elevates into the regions of abstraction, and, losing sight of sensible objects, perceives and contemplates the intellectual alone. One cause, one end, and one sole mode, form the whole of his perceptions. God is the cause, perfection the end, and harmonic representations the modes. What can be a more sublime idea! This plan of philosophy is replete with simplicity, and the views truly noble! but how void and destitute for speculation? We are not purely spiritual beings, nor have we the power to give a real existence to our ideas. Confined to matter, our rather dependent on what causes our sensations, the real substance can never be produced by the abstracted. I answer Plato in his own language, "The Creator realizes every thing he conceives; his perceptions engender existence: the created being, on the contrary, conceives nothing by retrenching them but from reality, and the production of his ideas do not amount to any thing."
Let us then content ourselves with a more humble and more material philosophy; and by keeping within the sphere Nature has allotted us, let us examine the rash steps and the rapid flight of those who attempt to soar beyond it. All this Pythagorean philosophy, which is purely intellectual, turns entirely on two principles, one of which is false and the other precarious: those are, the real power of abstraction, and the actual existence of final causes. To take numbers for real beings; to say that unity is a general individual, which not only represents every individual, but even communicates existence to them; to pretend that unity has the actual power to engender another unity nearly similar to itself, and constituting two individuals, two sides of a triangle, which can have no bound or perfection without a third side, or by a third individual, which they necessarily engender. To regard numbers, geometrical lines, and metaphysical abstractions, as efficient and real physical causes, on which the formation of the elements, the generation of animals and plants, and all the phenomena of Nature depend, seems to me to be the most absurd abuse of reason, and the greatest obstacle that can be put against the advancement of our knowledge. Besides, what can be more false than such suppositions? Admitting, with Plato and Malebranche, that matter does not exist, that external objects are only ideal images of the creative faculty, and that we perceive every thing in the Deity, must it be concluded from thence that our ideas should be of the same order as those of the Creator, or that they can produce existences? Are not we dependent on our sensations? Whether the objects that cause them are real or not; whether this cause of our sensations exists outwardly or inwardly; whether it be the Creator or matter we perceive, what does it signify to us? Are we less certain of being always affected in the same manner by the same causes? Have not our sensations an invariable order of existence, and a necessary relation between them and the objects? This, therefore, is what must constitute the principles of our philosophy; and what has no relation with it is vain, useless, and false in the application. Can a triangular harmony form the substance of the elements? Is fire, as Plato affirms, an acute triangle, and light and heat properties of this triangle? Air and water, are they rectangular and equilateral triangles? Is the form of the terrestrial element a square, because, being the least perfect of all the four elements, it recedes as much as possible from a triangle without losing its essence? Do the male and female embrace only to complete the triangle of generation? These platonic ideas have two very different aspects. In speculation they seem to flow from noble and sublime principles, but in application nothing but false and puerile consequences can be drawn from them.