There are nearly two hundred instances of can, can’t, cannot in our text, so I’ve chosen not to list them here. From Germanic roots and back to Proto Indo European, it meant primarily to know and the sense of to know how led to our most common meaning, to be able. But, dang, check this out:

An Old English preterite-present verb, its original past participle, couth, survived only in negation (see uncouth), but compare could. The present participle has spun off with a deflected sense as cunning.

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