Da Vinci was interested in art at a very young age but his father wanted da Vinci to get a job like him but he could not get him a career like his as he was illegitimate as he had been married to a peasant.  But Leonardo did show a great talent for drawing and his father thought he could be an apprentice to an artist.

Da Vinci was interested in vertical flight inventions such as helicopters and parachutes that were used in the sky for special purposes.  Leonardo’s focus on military technology and strategy lead him to the idea of aerial war machines.  As soon as he engaged in flying machines, it became his obsession.

Da Vinci was interested in the human anatomy and corpses after he saw drawings of a human skull.  Later, he was not interested anymore as he could not get his hands on any corpses to investigate further.  Eventually he came back and wanted to learn more about the human body and got interested in it again as he started cutting up lots of corpses to learn more about the structure of the human body.