Q. Why is the heart in the midst of the body? A. That it may impart life to all parts of the body; and therefore it is compared to the sun, which is placed in the midst of the planets, to give light to them all. Q. Why only in men is the heart on the left side? A. To the end that the heat of the heart may mitigate the coldness of the spleen; for the spleen is the seat of melancholy, which is on the left side also. Q. Why is the heart first engendered; for the heart doth live and die last? A. Because the heart is the beginning and original of life, and without it no part can live. For of the seed retained in the matrix, there is engendered a little small skin, which compasses the seed; whereof the heart is made of the purest blood; then of blood not so pure, the liver; and of thick and cold blood the marrow and brain. Q. Why are beasts bold that have little hearts? A. Because in a little heart the heat is well united and vehement, and the blood touching it doth quickly heat it, and is speedily carried to the other parts of the body, which gives courage and boldness. Q. Why are creatures with a large heart timorous, as the hare? A. The heart is dispersed in such a one, and not able to heat the blood which cometh to it; by which means fear is bred. Q. How is it that the heart is continually moving? A. Because in it there is a certain spirit which is more subtle than air, and by reason of its thickness and rarefaction seeks a larger space, filling the hollow room of the heart, hence the dilating and opening of the heart; and because the heart is earthly, the thrusting and moving ceasing, its parts are at rest, tending downwards. As a proof of this, take an acorn, which, if put into the fire, the heat dissolves its humidity, therefore it occupies a greater space, so that the rind cannot contain it, but puffs up and throws it into the fire. The like of the heart. Therefore the heart of a living creature is triangular, having its least part towards its left side, and the greater towards the right; and doth also open and shut in the least part, by which means it is in continual motion; the first motion is called _diastole_, that is, extending the breast or heart; the other _systole_, that is, shutting of the heart; and from these all the motions of the body proceed, and that of the pulse which physicians feel. Q. How comes it that the flesh of the heart is so compact and knit together? A. Because in thick compacted substances heat is strongly received and united. And because the heart with its heat should moderate the coldness of the brain, it is made of that fat flesh apt to keep a strong heat. Q. How comes the heart to be the hottest part of all living creatures? A. It is so compacted as to receive heat best, and because it should mitigate the coldness of the brain.