Thomas Aquinas died in the 13th century! What we call science today has little relationship to what they called science back then. In fact, it is much more tightly defined now than it was in the 19th century, which is when the "theory" of evolution was propounded. I assert that if the "theory" of evolution was to be put forth today, it would not be acceptable as a theory.
Heck, the only reason it probably still is a theory is that the scientific "establishment" has its back up because it feels it is being attacked by "trailer park fundamentalists". If the Christians had ignored it, instead of politicizing it, the so called theory would already have been reworked several times. As it is, any attacks on the "theory" of evolution tends to get grabbed by the creationists, and so most scientists just avoid the subject. They don't want their tenures/grants/etc. to be threatened.
sci·ence Pronunciation Key (sns)The word has two most significant senses and Aquinas was using second sense, but even the first sense (in bold) can apply. The medieval dictum that "theology is the queen of the sciences" is as true today as it was 700 years ago, and good science is as dependent on good theology as it was 700 years ago. It's no accident that Western natural science arose from within a Christian worldview.
n.
1.
a. The observation, identification, description, experimental investigation, and theoretical explanation of phenomena [Intelligent Design].
b. Such activities restricted to a class of natural phenomena.
c. Such activities applied to an object of inquiry or study.2. Methodological activity, discipline, or study.