He is too practical, too much wrapped up in the problems of his time.
Since Copernicus, it has been evident that Man has not the cosmic importance which he formerly arrogated to himself.
So you're not supposed to philosophize on matters pertaining to humans and their practical problems nor of "cosmic importance." What exactly are you supposed to philosophize about?
Apparently, this is Bertrand Russell, so it makes a lot more sense. I guess philosophers are supposed to only concern themselves with formal logic and writing three volume works to prove 1+1=2. That and critiquing movies you haven't seen like Zizek.