There is much pleasure to be gained from useless knowledge.

Russell’s point is that “usefulness” is not the only measure of knowledge. Facts, theories, languages, and histories that do not obviously help one earn money or solve an immediate problem can still enlarge perception, deepen aesthetic and intellectual enjoyment, and provide resources for reflection. The phrase also challenges a purely instrumental view of education: even when knowledge has no direct application, it can be valuable because it nourishes curiosity, gives perspective on human affairs, and offers the distinctive pleasure of understanding. Implicitly, Russell suggests that a society that prizes only the practical risks losing the joys and freedoms that come from learning without ulterior purpose.