etymology of 'trade'

An etymology lesson from Gil Guillory:

trade

c.1375, "path, track, course of action," introduced by the Hanse merchants, from M.Du. or M.L.G. trade "track, course" (probably originally of a trading ship), cognate with O.E. tredan (see tread). Sense of "one's habitual business" (1546) developed from the notion of "way, course, manner of life;" sense of "buying and selling" is first recorded 1555. The verb is 1548, from the noun. Trade wind (1650) has nothing to do with commerce, but preserves the obsolete sense of "in a habitual or regular course." Trademark first attested 1838; in figurative sense, 1873.

http://www.etymonline.com/index.php?search=trade

So the etymological roots of "trade" and "tradition" are probably the same. Your trade is what you traditionally do. So I guess the highwayman really does have a trade, whether he exchanges anything or not.

No, see, here it gets complicated again:

tradition

c.1382, from O.Fr. tradicion, from L. traditionem (nom. traditio) "delivery, surrender, a handing down," from stem of tradere "deliver, hand over," from trans- "over" + dare "to give" (see date (1)). The notion in the modern sense of the word is of things "handed down" from generation to generation.

http://www.etymonline.com/index.php?search=tradition

So the Latin tradere (tradeo: I deliver) seems to me to be as likely a root for modern English 'trade' as the medieval germanic roots etymonline cites. If nothing else, we have a hint that the "giving" of trans-dare is present in the early and late meanings, even if it faded in the middle.