Hebrews 5:14

belongeth to them that are of full age The solid food of more advanced instruction pertains to the mature or "perfect."

by reason of use "Because of their habit," i.e. from being habituated to it. This is the only place in the N.T. where this important word ἕξις habitusoccurs.

their senses Their spiritual faculties (αἰσθητήρια. It does not occur elsewhere in the N.T.)

exercised Trained, or disciplined by spiritual practice.

to discern both good and evil Lit., "the discriminationof good and evil." By "good and evil" is not meant "right and wrong" because there is no question here of moral distinctions; but excellence and inferiority in matters of instruction. To the natural man the things of the spirit are foolishness; it is only the spiritual man who can "distinguish between things that differ" and so "discriminate the transcendent" (1 Corinthians 2:14-15; Romans 2:18; Philippians 1:9-10). The phrase "to know good and evil" is borrowed from Hebrew (Genesis 2:17, &c), and is used to describe the first dawn of intelligence (Isaiah 7:15-16).