Swammerdam was convinced that the creation, or generation, of all creatures obeyed the same laws. Having studied the reproductive organs of men and women at university he set out to study the generation of insects. He had devoted himself to studying insects after discovering that the "king" bee was indeed a queen bee. Swammerdam knew this because he had found eggs inside the creature. But he did not publish this finding. In 1669 Swammerdam was visited by Cosimo II de' Medici and showed him another revolutionary discovery. Inside a caterpillar the limbs and wings of the butterfly could be seen (now called the imaginal discs). When Swammerdam published "The General History of Insects, or General Treatise on little Bloodless Animals" later that year he not only did away with the idea that insects lacked internal anatomy, but also attacked the Christian notion that insects originated from spontaneous generation and that their life cycle was a metamorphosis. Swammerdam maintained that all insects originated from eggs and their limbs grew and developed slowly. Thus there was no distinction between insects and so called "higher animals". Swammerdam declared war on "vulgar errors" and the symbolic interpretation of insects was, in his mind, incompatible with the power of God, the almighty architect.