So it can be surprising to hear devotees of Russian say the alphabet is the easiest part of the job. The Cyrillic script, like the Roman one, has its origins in the Greek alphabet. As a result, some letters look the same and are used near identically. Others look the same but have different pronunciations, like the p in Cyrillic, which stands for an r-sound. For Russian, that cuts the task down to only about 20 entirely new characters. These can comfortably be learned in a week, and soon mastered to the point that they present little trouble. An alphabet, in other words, is just an alphabet. A few tricks aside (such as the occasional omission of vowels), other versions do what the Roman one does: represent sounds.

This is easily illustrated with concrete vocabulary. Sometimes the meanings of foreign words and their English equivalents overlap but don’t match exactly. Danish, for instance, does not have a word for “wood”; it just uses “tree” (trae). Or consider colours, which lie on a spectrum that different languages segment differently. In Japanese, ao traditionally refers to both green and blue. Some green items are covered by a different word, midori, but ao applies to some vegetables and green traffic lights (which, to make matters more confusing, are slightly blueish in Japan). As a result, ao is rather tricky to wield.

Life becomes tougher still when other languages make distinctions that yours ignores. Russian splits blue into light (goluboi) and dark (sinii); foreigners can be baffled by what to call, say, a mid-blue pair of jeans. Plenty of other “basic” English words are similarly broken down in their foreign corollaries. “Wall” and “corner” seem like simple concepts, until you learn languages that sensibly distinguish between a city’s walls and a bedroom’s (German Mauer versus Wand), interior corners and street corners (Spanish rincón and esquina), and so on.

These problems are tractable on their own; you don’t often have to refer to a corner in casual conversation. But when other languages make structural distinctions missing from your native tongue—often in the operation of verbs—the mental effort seems never-ending. English has verbs-of-all-work that seem straightforward enough until you try to translate them. In languages like German, “put” is divided into verbs that signify hanging, laying something flat and placing something tall and thin. “Go” in Russian is a nightmare, with a suite of verbs distinguishing walking and travelling by vehicle, one-way and round trips, single and repeated journeys, and other niceties. You can specify all these things in English if you want to; the difference is that in Russian, you must.

“Evidential” languages require a verb ending that shows how the speaker knows that the statement made is true. Turkish is one of them; others, such as a cluster in the Amazon, have particularly complex—and obligatory—evidentiality rules. Many languages mark subjects and direct objects of sentences in distinct ways. But in Basque, subjects of intransitive verbs (those that take no direct object) look like direct objects themselves, while subjects of transitive verbs get a special form. If Martin catches sight of Diego, Basques say the equivalent of “Martinek sees Diego.”

In the end, the “hard” languages to learn are not those that do what your own language does in a new way. They are the ones that make you constantly pay attention to distinctions in the world that yours blithely passes over. It is a bit like a personal trainer putting you through entirely new exercises. You might have thought yourself fit before, but the next day you will wake up sore in muscles you never knew you had.