"As a virtue, a discerning individual is considered to possess wisdom, and be of good judgement; especially so with regard to subject matter often overlooked by others." http://en.wikipedia.org/wiki/Discernment
Definition of discerning - having or revealing keen insight and good judgment. Examples of it in a sentence: She had a discerning eye for color. He was a discerning critic.
When it has a subject, verb, punctuation, capitalization, a predicate, and a complete thought. A sentence is a sentence when it is handed down by a judge (or a magistrate).