It took a long time to find out the function of blood in the body. Asimov traces its history from 400 B.C.—the time of the great Greek doctor Hippocrates—to Aristotle and Praxagoras, to Galen and Vesalius, to Harvey and other great physicians. Each contributed some knowledge about the heart, arteries, and veins, and then went on to further discoveries. Bit by bit Asimov unravels the mystery of the blood’s function in the body.

Excellent for young readers, this introduction to blood and the stuff in it might be less interesting to an adult than The Bloodstream or The Human Body, which cover the same ground.