Discussion is the introduction...Philosophy is different from what u think it is...In our life we tend to seek answer, answer a question and next u get is another question...and so on....But in philosophy, what we do is question back the answer, is like moving backward ...therefore my opinion is that philosophy is the core of anything u could aware off (knowledge)....IN philosophy, the valuable lesson is learn not to know but to understand...Hence, philosophy is unknowable but describable...
Imagine the centre is the begining of knowledge, in order to produce or increase the diameter of circle, u need to keep answering questions, keep knowing something that u dono......... Any degree in circle symbolize the different field of knowledge, range from science to religion...Well, let said that u had the circle, a big one, and now u realised there is something missing ,and  u're starting to question what is the purpose of all we do (what is the purpose of life??)...Therefore u tend to question back everything...finding back the centre which produce the circle u had before