Is it farther or further?
1650s, from French didactique, from Greek didaktikos "apt at teaching," from didaktos "taught," past participle of didaskein "teach," from PIE root *dens- "wisdom, to teach, learn." Related: Didactically; didacticism.
didactic di·dac·tic (dī-dāk'tĭk)
Of or relating to medical teaching by lectures or textbooks as distinguished from clinical demonstration with patients.
of literature or other art, intended to convey instruction and information. The word is often used to refer to texts that are overburdened with instructive or factual matter to the exclusion of graceful and pleasing detail so that they are pompously dull and erudite. Some literature, however, is both entertaining and consciously didactic, as, for example, proverbs and gnomic poetry. The word is from the Greek didaktikos, "apt at teaching."