Who is St. Thomas Aquinas from Catechism of the Catholic Church and what is their importance?

This Catholic Saint comes up during the discourse on morality as part of a larger discussion of the Christian life and lifestyle. This man is famous amongst Catholics and amongst philosophers in general for his thought and his writings. A champion of Christian theology within a context of challenging and brilliant philosophers of other schools of thought, St. Thomas Aquinas was able to articulate a convergence of Christian and Aristotilian philosophy.