The trees in the garden are light or knowledge. This shows that there were some knowledge that Adam did not come into, even when he was created. There were trees of knowledge put around him so he could learn. If Adam had attained the state of all the knowledge he was meant to come into, he would not have been able to fall. There was a commandment God gave to Adam that if he had obeyed, would have brought him into a higher life which would not have allowed him to fall.