In the centenary year of his death, one of the best letter writers in English receives his due in the hands of Stevenson authorities Booth (d. 1968) and Mehew. Eight volumes of letters will be published, restoring more than twice as many to print as we'd had heretofore. The first two volumes find Stevenson focusing on a quartet of correspondents: his mother; his artist cousin, Bob Stevenson; his friend Sidney Colvin, an art historian; and Mrs. Francis Sitwell (Stevenson's muse, with whom he had relations that seem to have veered close to the carnal, then off to the maternal). Stevenson disappoints his father by rejecting both a career in engineering and the family's orthodox Scotch Calvinism. Then, while recovering from illness (due in part, no doubt, to stress) on the French Riviera, he begins writing in earnest--first sketches, then essays, and finally tales. He's admitted to the Scottish bar (mostly to mollify his parents), but literary life leaves him no taste for the law, which he lets languish. On a visit to the Continent he meets his eventual wife, Fanny Osbourne, of Oakland, Calif. Stevenson's youthful letters to his mother may be the most remarkable of all- -travel notes, with every color of a sky and angle of a slope recorded: ``At the north of town stands Fort Charlotte, founded, as I hear, by Cromwell. It overhangs the water with a circuit of heavy grass grown walls, backed by mounds supported by ruinous buttresses and pierced by some four arched gateways. The sea-pink blooms thickly among the lichened crevices of the old stonework.'' With an admittedly ``elastic'' temper, his lows are low but never stiffen into a pose: ``On red-letter days, I manage to get enough excitement for a tolerably happy life.'' To read Stevenson gaining confidence in his art is to understand the humble yet unerring precision that invests all of his great fiction so memorably.