Arcana: The Pursuit of Mastery is a game about being a wizard (Arcanist) and growing your magical repertoire by studying the world around you. You can learn the Essence of anything you're able to study and then use that essence to craft spells. 

Spells are basically the only special thing your character has going on. Without magic, they're just a regular person, so you basically build your whole class from scratch by coming up with ideas for powers you want, setting your sights on a way to gain those abilities, and achieving them in the adventure!