Thanks for that definition. I believe that when my professor said that there was no natural theology, according to Calvin, he meant that Calvin was reacting against Aquinas' natural theology for which I found a definition
here.
For Thomists, Natural Theology is the study of what can be known about God apart from revelation.
Thus, for Aquinas, on the one hand, there are things that God has revealed about Himself which could be known by reason alone (Natural Theology), and on the other hand, there are things that He Himself alone knows about Himself, which He reveals to others, and which are, and must always be in this life, objects of religious belief (Sacred Doctrine). The Catholic Theologians, and Calvin are pretty unified on this idea. Natural Theology is something that crosses Catholic-Protestant lines. BTW, the source was the link you gave to me, thanks,...it does seem to read like Calvin.