We are not such optimists as were our teachers and parents. We do not have to equate “progress” with every δf(t) if δt > 0, t being the time. Instead of a field of brilliant success like hydrodynamics or electromagnetism, I shall discuss one accursed by misunderstanding, irrelevance, retreat, and failure: thermodynamics in the 19th century. You will not be surprised, consequently, by my use of a delta to define progress, since thermodynamics is the kingdom of deltas. However, in this lecture I will not use a delta again.