Universities offer courses in a wide variety of disciplines. At some point, generally by the end of the second year, students are required to declare a major. In some cases, students begin classes in a program of study from the minute they enter the university.

Some college freshmen seem to have been called to a profession at an early age, 

and their determination to become a teacher, or doctor, or engineer has never wavered.

On the other hand, most freshmen are waiting for the fires of inspiration to be lit.

请问文中的the fires of inspiration什么意思？

fire在字典里查到的是“狂热的情感，激情”并且是不可数名词，文中却加了“s”。

inspiration在文中是不可数名词“灵感”的意思吗？