Brooke Holmes (Princeton University) gives a talk for the Causing Health and Disease: Medical Powers in Classical and Late Antiquit conference, held at Corpus Christi College on 21st-22 September 2012. One of Galen's basic philosophical commitments is to the Platonic idea of the Demiurge. No other explanation of the intelligent organization of living beings, he argues, is remotely plausible. But how is the rational design of the Demiurge actually realized in matter, not just at the moment of creation but over the course of an organism's life? In this paper, Holmes examines Galen's treatment of what he calls the natural faculties (physikai dynameis) as the vehicles of immanent intelligence of living beings, paying particular attention to the relationship of the treatise On the Natural Faculties to other later works, such as On My Own Opinions and On the Formation of the Fetus. Holmes is primarily interested in cases where the concept of the natural faculties is strained, such as the moment of conception and at the boundary between animate and inanimate beings. By focusing on these occasions, we can pose the question: How much intelligence does the concept of dynamis sustain in Galen?