'He who speaks no foreign language, does not know his mother tongue'

I understood it to mean that one needs a comparitive language to highlight the mechanisms and assumptions in one's own language. What seems natural and "god-given" becomes worthy of investigation when other ways are shown to be equally valid (or widely held). This is also true of political, cultural, religeous and social systems.

What may be of interest is how different should the other language be to be of best use in teaching us more about our own language. Are there particular languages which are best suited for this job? (On English would it be Latin, Klingon?) Or can we get the best instruction from a range of languages? My own natural inclination is the latter with no real evidence except that I know I have learnt something from each language I have been exposed to.

Rod