“In like a lion, out like a lamb” has always seemed a straightforward enough proverb: when March starts, it’s still winter, and by the end of the month spring has begun. True, in many climates the weather hasn’t quite reached the lamb stage by the end of the month—it’s more like a surly cat, maybe, or one of those awful territorial honking geese. But we get the idea. I have seen the phrase referred to as an “eighteenth-century saying” in more than one unreliable Internet source, while Wikipedia calls it “an old Pennsylvania” saw.