Figuring out if a given person has the capacity to study the magical arts isn’t hard.
Firstly, you need to get a clear idea on whether the person in question has a decent memory. There are operating procedures, formulas and incantations to be mastered in the study of the magical arts.
Secondly, you need to get a clear idea on whether the person in question is capable of keeping secrets. You have to remember that when a person is inducted into the magical arts, chances are that he or she will be required to keep certain secrets. And if the person in question happens to be one of those folks who feel the impulsion to show off everything they know, then chances are that he won’t be in a position to study magical arts.
Thirdly, you need to get a clear idea of whether the person in question has the ability to understand complex things. You can gauge this with relatively simple things. For instance, if the person in question can’t make sense of the workings of a virtual school counselor program like the one described in this page, there is very little chance of him or her being in a position to understand the more intricate magical arts.