How did Italian High Renaissance art reflect humanist thought of the time?

There was a sudden interest in the individual. Art of the Middle Ages was generally anonymous--the artist did not create the work for self-expression but to glorify God, and therefore did not sign the work nor create a record of doing it. In the Renaissance, on the other hand, artists became famous for their work, and even engaged in self-portraiture--Botticelli and Raphael and others even placed themselves in religious or allegorical scenes that they painted.

There were also great changes in content. Medieval art only deals with Christianity or, occasionally, serves the purposes of wealthy nobility. Renaissance art celebrates individuals of the middle class; there are thousands of portraits of merchants, scholars, musicians, wives, and children.

Humanism considers that people can solve difficulties on their own, without the help of God. Many non-Christian works in the Renaissance support such a philosophy, especially Raphael's "School of Athens".

The naturalistic way of portraying the human body in the Renaissance--full anatomical accuracy, and frequently nude--is in stark contrast to the way that the Medieval artist abstracted the human body, in some cases making it seem as if their portraits and statues of saints have no body beneath their robes.