This tangent is really off of Doom's post, though. I know you're just cracking on psych.
There are really two parallel aspects to the evolution of thought, one being that an individual's ideas are built on the works of his or her forbearers, the other being that the process of developing those ideas is itself shared. What's interesting about Freud is that he's never been as important to the field of psychology as he has to, of all things, literature and writers. He certainly deserves credit for developing a system to conceptualize abstract functions of the conscious mind, but that's really just a minor contribution to the field as a whole. The most I've ever had to use Freud was in studying his use of symbols for an English paper, and that in itself is a testament to how building a framework for thought can cross disciplines and inspire creativity in areas that might not be related (although, practically speaking, literature was psychology before there was actual psychology). It's appropriate that you bring up Newton's cross discipline importance because, in this light, even his foray in alchemy starts being a relevant contribution.
Anyway, you should bring this all up when you're letting your professor micromanage on top of you.