[Note: this turned out to be a Biblical argument when I didn’t originally intend for it to be; I eventually want to make a non-Biblical one, too. My apologies to non-Christian readers.]
Philosophy, the love of wisdom, is good for its own sake. Wisdom can indeed be a means to an end (Pro 24:3 “Through wisdom is an house builded”), but this is not the main reason to pursue it.
Wisdom is valuable in herself (for wisdom is often personified). Solomon, in speaking of wisdom, says, “She [is] more precious than rubies: and all the things thou canst desire are not to be compared unto her” (Pro 3:15).
And, if you happen to be Jewish or Christian, you are commanded to be a lover of wisdom (or in Greek, a “philosopher”): “Get wisdom … love her, and she shall keep thee” (Pro 4:5-6). The Biblical definition, though slightly different, is not that far off from what Socrates possessed. I’ve read only one chapter of The Republic, so I don’t have much to go off of. But let’s compare the wisdom of Solomon to the wisdom of Socrates and see if there’s overlap:
Solomon: The mouth of the just bringeth forth wisdom (Pro 10:31)I think there’s quite a bit of overlap. The point is that Wisdom is the same to Socrates and Solomon. They were describing the same thing (the latter with the help of God directly). Both were concerned with how a person should live his or her life. Both thought deeply about these matters. They both sought wisdom before wealth or production. In the case of Solomon, he sought wisdom first, and all the ‘pragmatic’ things (wealth and fame) were added to him because of it. We should aspire to be the same way.
Socrates: …the just man is like the wise and the good...justice is indeed both wisdom and virtue (350c, 351a)
Solomon: Happy [is] the man [that] findeth wisdom (Pro 3:13)
Socrates: …the just man is happy (345a)
Solomon: Only by pride cometh contention: but with the well advised [is] wisdom. (Pro 13:10)
Socrates: it’s injustice that produces factions, hatreds, and quarrels among themselves, and justice that produces unanimity and friendship. (351d)
Part 1; Part 2; Part 3