Full Idea
True philosophers concern themselves first and foremost to take clearly observed facts as their point of departure.
Gist of Idea
Philosophy must start from clearly observed facts
Source
Galen (The soul's dependence on the body [c.170], Kiv.11.817)
Book Reference
Galen: 'Selected Works of Galen', ed/tr. Singer,P.N. [OUP 1997], p.173
A Reaction
I love this one, especially the desire that the facts be 'clearly observed'. That, thank goodness, eliminates quantum mechanics. If you don't love history and the physical sciences, you are not a philosopher. Oh, and reliable gossip.