Eunuchs who have been deprived of only their testicles, still feel an irritation in the parts that are left, and have the external mark of desire even more frequently than other men. Those parts, however, remain, as to size, nearly in the same state as before the operation; and if this is performed at the age of seven years, an eunuch of twenty is, in this respect, as a child of seven. If it is not, on the contrary, performed till the time of puberty, or a little after, the size is nearly the same as that in other men.
Between the parts of generation and the throat there are particular connections, altho' we know not the cause. Eunuchs have no beard, their voice, though shrill and powerful, is never of a deep tone; and not unoften does the throat become the seat of the secret distemper. The correspondence which certain parts of the body have with others, widely remote and of a different nature, ought to be more generally observed; but we pay too little attention to effects, when we do not surmise their causes. Thus it is, that though in effect the action of the animal machine in a great measure depends upon them, these different affinities remain unexamined with that care they deserve. In women, there is a great correspondence between the matrix, the breasts and the head: and how many beneficial facts of this kind might, be found if a few able physicians would direct their studies to such discoveries! These muscles, veins, arteries,, and nerves, which they describe with so much accuracy, and with so much fidelity, are not the springs which give life to our organization. There resides in organized bodies certain internal powers, which are by no means guided by the laws of gross mechanism; instead of attempting to know the nature of those powers by their effects, the very ideas of them have been treated as ideal, and endeavours have been made to discard and banish them from philosophical researches. These very powers, nevertheless, have maintained their importance in gravitation, in the phenomena of electricity, &c. But, however evident and universal they may be, as their action is wholly internal, and they are solely objects of reason, it is with a kind of unwillingness that they are admitted; inclination still leads us to judge from external appearances; we form a notion, that in those appearances every thing consists, and that we are not allowed to penetrate farther; and thus we effectually turn our hacks upon that which might lead to refined information.