theory

A great many wars have been fought over the religion of quality code. For who has not had a peer slain by the zealots of TDD? What programmer among ye has not spent longer than their heart desired on a pull request to DRY their code further? Who has not seen a code base lain asunder by the conquest of OOP?

Jack of all trades master of none.

Jack of all trades master of one?

Jack of all trades master of none... but often better than a master of one?

What the heck was the original quote, and why would learning more programming languages be helpful?