This chapter considers a selection of approaches from Aristotle’s biological work in order to show the quality, seriousness, and philosophical power of Aristotle’s science of biology. It seeks to show the remarkable insight of Aristotle’s scientific work in this field. His observations are becoming increasingly pertinent in an age of epigenetics and evo-devo, not less. Even more significant, however, is the fact that the great philosopher Aristotle produces a sophisticated philosophy based upon biology and hence provides us with a philosophical basis for biology. Aristotle’s philosophy seeks to explain the biological fact that a human foetus grows into a human being and the matures into an ethical human being. The ultimate subject of Aristotle’s whole project is not the meaning of matter or God, but life as ultimately expressed in the human being. Aristotle’s approach is not anthropocentric but merely argues that we must surely include our own existence within any explanation of the world.