“The essence of immorality is the tendency to make an exception of myself,” wrote the philosopher Kant

That’s actually a slightly botched Jane Addams quote:

I once heard Father Huntington say that the essence of immorality is the tendency to make an exception of one’s self and I would like to add that to consider one’s self in any wise unlike the rank and file of human life is to walk straight toward the pit of self righteousness.

Source.