… is from page 229 of Karl Popper’s 1972 collection, Objective Knowledge; specifically, it’s from Popper’s profound 1965 essay “Of Clouds and Clocks” (original emphasis):
For obviously what we want is to understand how such non-physical things as purposes, deliberations, plans, decisions, theories, intentions, and values, can play a part in bringing about physical changes in the physical world. That they do this seems to be obvious pace Hume and Laplace and Schlick. It is clearly untrue that all those tremendous physical changes brought about hourly by our pens, or pencils, or bulldozers, can be explained in purely physical terms, either by a deterministic physical theory, or (by a stochastic theory) as due to chance.
