Instead of being completely arbitrary, the meaning of many idioms is "motivated" by their original, literal usage. In an FLT context, this offers the possibility of presenting idioms in ways that promote insightful learning rather than "blind" memorization. Associating an idiom with its etymology has been shown to enhance retention. This effect seems in accordance with Dual Coding theory, as the etymological association is likely to call up a mental image of a concrete scene which can be stored in memory alongside the verbal form. The present study explores the possibility of taking this technique beyond "mere" mnemonics. We report a series of experiments that were set up with the participation of students of English in higher education. The results show that knowledge of the origin of idioms can effectively help learners comprehend their figurative meaning. Not only does the problem-solving task of inferring idiomatic meaning on the basis of etymological information appear feasible, it seems to facilitate recall, too, as predicted by Levels-of-processing theory in general. Finally, the results suggest that knowledge of the origin of certain idioms can help learners estimate whether they might be typical of informal discourse. (Contains 2 tables and 2 figures.)