Works Necessary for Salvation in Luther's Theology?

I cite the following approvingly. Don't ever let any Roman Catholic say that works are not essential in Luther, not to mention the Protestant stream (flowing from Scripture, as it does).

From the Preface to the Wittenberg Edition of Luther's Writings:

Neither councils, fathers, nor we, in spite of the greatest and best successes possible will do as well as the Holy Scriptures, that is, as well as God himself has done. (We must, of course, also have the Holy Spirit, faith, godly speech, and works, if we are to be saved.)   

—Luther's  Works, vol. 34, Career of the Reformer, p. 284.