Recently we have spent some time getting familiar with the basic outlines of Thomist philosophy. Thomas Aquinas is so important in the development of Christian culture that one must necessarily deal with his brilliant output at some level. The term usually given to his kind of work is "Scholasticism," and Aquinas was certainly not the only Medieval to generate such material.
Also important to note is that Scholasticism did not really die with the Middle Ages, though in popular thought the two are nearly always put together--i.e., Scholasticism is a superrationalistic form of unnecessary disputation about things like how many angels can dance on the head of pin, a form of discourse that those benighted Medieval Catholics got lost in and from which Protestants rescued the Church.
In fact, Protestants developed their own forms of Scholasticism, and this article is useful for getting a feel for the development of that tradition, one that most Protestants are entirely ignorant of.