Meditations, Book 10, Section 26

Marcus Aurelius — The Emperor

From a man comes the seed. Once it is cast into the womb, the man has no more to do with it. Another force takes over the work and in time brings a child to completion — that wonderful result from such a simple beginning! Again, a man swallows food down his throat. Once it is down, he has no more to do with it. Another force takes over and distributes this food into the senses and emotions, into life and strength. It does many other marvelous things that belong to being human. You must learn to observe and contemplate these things that work so secretly and invisibly. Not just the things themselves, but also the power by which they happen. You can see this power, though not with your physical eyes, as clearly as you can see the visible cause of anything rising or falling.

Marcus Aurelius — The Emperor Original

From man is the seed, that once cast into the womb man hath no more to do with it. Another cause succeedeth, and undertakes the work, and in time brings a child (that wonderful effect from such a beginning!) to perfection. Again, man lets food down through his throat; and that once down, he hath no more to do with it. Another cause succeedeth and distributeth this food into the senses, and the affections: into life, and into strength; and doth with it those other many and marvellous things, that belong unto man. These things therefore that are so secretly and invisibly wrought and brought to pass, thou must use to behold and contemplate; and not the things themselves only, but the power also by which they are effected; that thou mayst behold it, though not with the eyes of the body, yet as plainly and visibly as thou canst see and discern the outward efficient cause of the depression and elevation of anything.