“Among the innumerable mortifications which waylay human arrogance on every side may well be reckoned our ignorance of the most common objects and effects, a defect of which we become more sensible by every attempt to supply it. Vulgar and inactive minds confound familiarity with knowledge and conceive themselves informed of the whole nature of things when they are shown their form or told their use; but the speculatist, who is not content with superficial views, harasses himself with fruitless curiosity, and still, as he inquires more, perceives only that he knows less.”
Samuel Johnson, The Idler, Saturday 25th November 1758
Knowledge has its strange inversions, as Dr. Johnson notes, and knowledge of a language is no exception. The more we know of a subject, the more conscious we become of our ignorance.
Richard Feynman (1918-1988) for example, physicist and Nobel laureate, talked in an interview of his father’s refusal to placate his son with untruths or easy answers. It was not only the fact that his father did not know the answers to various of Feynman’s infant questions, but that no one really knew which piqued the infant laureate’s interest; and with retrospect he admired that his father had clearly understood the difference between knowing the name of something (inertia, in the example he cites) and actual understanding (we still have no idea why objects in the physical realm should be governed by inertial force).
Thus it is with language. When one of my students asked me recently, for example, why it is possible both to widen or broaden your horizons or your perspective, but not possible for travel to widen the mind; the correct answer should have been, no one knows. Some phrases and collocations harden into invariable idiom; others stay loose and flexible and interchangeable. Similarly, and more arcanely, it is not true that there is no difference between broadening your horizons and widening them. But we struggle to articulate it. Is that that broadening suggests something more spiritual, widening more mechanical? Perhaps. Widening your horizon might be borrowing something from widening your perspective, which involves stepping back from your object; broadening your horizons might echo the idea of travel broadening the reach of your mind as you move towards and assimilate new objects.
Who knows, or even really cares? Most of us in our daily lives work to a principle of good enough. Good enough does not work in physics, nor in many other areas of fine expertise, but working within reasonable tolerances is the stuff of language learning. There is no such thing as perfection: only more or less successful or unsuccessful transactions, or interactions, depending on the goal. No amount of spade-work will fill up the abyss of ignorance, even for a native speaker; but that does not render the constant work ineffective or inappropriate. We cannot all be, all of the time, speculatists, but must be satisfied with the workings of our vulgar and inactive minds.