In his writings Knox synthesised a perspective on nature from three of the most influential natural historians of his time. From Cuvier, he took a consciousness of the great epochs of time, of the fact of extinction, and of the inadequacy of the biblical account. From Étienne Geoffroy St-Hilaire and Henri Marie Ducrotay de Blainville, he gained a spatial and thematic perspective on living things. If one had the skill, all living beings could be arranged in their correct placing in a notional table, and one would see both internally and externally the elegant variation of their organs and anatomy according to the principles of connection, unity of composition and compensation.