1) Aristotelian ideal 2) The happy medium 
[philosophy] In philosophy, especially that of Aristotle, the `golden mean` is the desirable middle between two extremes, one of excess and the other of deficiency. For example, in the Aristotelian view, courage is a virtue, but if taken to excess would manifest as recklessness, and if deficient as cowardice. To the Greek mentality, it was ...
(from the article `ethics`) ...as they were popularly understood in his day, specifying in each case what is truly virtuous and what is mistakenly thought to be so. Here he ...
[n] - the middle between extremes
The proportion of the division of a line so that the smaller part is to the larger partwhat the larger part is to the whole. This may be applied to the lengths of the sides ofa rectangle. Classically this ratio has been used to define the size of objects as it isthought that this ratio yields objects that are pleasing to the eye. It is equal to the...
noun the middle between extremes
the perfect moderate course or position that avoids extremes; the happy medium. · See