Jowett: anagke

ananke = Necessity

Soc. Why yes, the end I now dedicate to God, not, however, until I have explained anagke (necessity), which ought to come next, and ekousion (the voluntary). Ekousion is certainly the yielding (eikon) and unresisting — the notion implied is yielding and not opposing, yielding, as I was just now saying, to that motion which is in accordance with our will ; but the necessary and resistant being contrary to our will, implies error and ignorance ; the idea is taken from walking through a ravine which is impassable, and rugged, and overgrown, and impedes motion — and this is the derivation of the word anagkaion (necessary) an agke ion  , going through a ravine. But while my strength lasts let us persevere, and I hope that you will persevere with your questions. CRATYLUS