_To learn_ is the infinitive, used as a noun, the object of the verb
_wish_. The infinitive also has an object, to learn--_what?_ _My lesson_
is the object of the infinitive _to learn_. We also have an adverb
modifier in the adverb _quickly_, which tells _how_ I wish to learn my
lesson. So the infinitive retains its verb nature, in that it may have
an object and it may be modified by an adverb.