What did he do to come to this point?
While Darwin was at Christ's College, botany professor John Stevens Henslow became his mentor. After Darwin graduated from Christ's College with a bachelor of Arts degree in 1831, his mentor suggested him for a naturalist's position aboard the HMS Beagle. The trip abroad was to take a 5 year trip around the world. Over the course of the trip, he collected different types of animals, fossils, and plants. He researched and experimented. This gave him the opportunity to closely observe zoology, botany, etc.
Upon his arrival in England, he began to record all the information he observed.