Philosopher

The reason, I suppose, why uneducated people have fallen into this darkest of all errors is because they are incapable of looking far enough back into the past; this is what makes them fail to realize that the people who first created civilization were the philosophers. ~ Cicero

In studying a philosopher, the right attitude is neither reverence nor contempt, but first a kind of hypothetical sympathy, until it is possible to know what it feels like to believe in his theories, and only then a revival of the critical attitude, which should resemble, as far as possible, the state of mind of a person abandoning opinions which he has hitherto held. ~ Bertrand Russell

The definition is therefore amended: the philosopher is a man who loves the “vision of Truth.” ~Bertrand Russell

Artistotle says

And that all these attributes belong most of all to the philosopher is manifest. He, therefore, is the dearest to the gods. And he who is that will presumably be also the happiest; so that in this way too the philosopher will more than any other be happy.

i.e. the pursuit of Philosophy is the activity bringing the most Will to power.

Though, specialization is in-human.

Be a philosopher, but amidst your philosophy, be a man ~ Hume