in Thoreau’s Journal:

This is the coolest day thus far, reminded me that I have only a half-thick coat on. The easterly wind comes cold into my ear, as yet unused to it. Yet this first decided coolness — not to say wintriness — is not only bracing but exhilarating and concentrating our forces.

So much the more I have a hearth and heart within me. We step more briskly, and brace ourselves against the winter.