10. Relearning is relatively fast.

Forgetting is the unavoidable fate of any skill we don’t use regularly. Hermann Ebbinghaus found that knowledge tapers off at an exponential rate — most quickly at the beginning, slowing down as time elapses.

Relearning is a nuisance, especially since struggling with previously easy problems can be discouraging. Yet it’s no reason not to learn deeply and broadly — even forgotten knowledge can be revived much faster than starting from scratch.