Zealous gentleness?

I don't really have a conclusion for this post, but I was reading Galatians today and noticed an interesting paradox of sorts. Zealous vs. gentle. Paul talks about zealousness being a great thing, and how the church at Galatia started out with a lot of it. But then he also talks about having a spirit of gentleness, and how we should use it to serve one another. In my mind, these two things don't really go together. You can't be zealous and gentle at the same time, can you? Can you be gently zealous? Zealously gentle? Now that I type it, it makes a modicum of sense, but it still seems rather challenging...