Quintilian Institutio Oratoria 1.6.38

[38] But Varro had such a passion for derivations that he derived the name merula from mera uolans on the ground that it flies alone! Some scholars do not hesitate to have recourse to etymology for the origin of every word, deriving names such as Rufus or Longus from the appearance of their possessor, verbs such as strepere or murmurare from the sounds which they represent, and even extending this practice to certain derivatives, making uelox for instance find its origin in uelocitas, ¹ as well as to compounds and the like: now although such words doubtless have an origin, no special science is required to detect it, since it is only doubtful cases that demand the intervention of the etymologist.