Information about the life of Roger Bacon is slim; scholars have invented conflicting chronologies and have assumed a great deal about his career. The commonly accepted view is that set out by Theodore Crowley and developed by David C. Lindberg. It takes Bacon's indirect remarks in the Opus Tertium (Third Work, circa 1267) as the basis for a firm setting of the whole chronology: "I have laboured much in sciences and languages, and I have up to now devoted forty years [to them] after I first learned the alphabet; and I was always studious. Apart from two of these forty years I was always [engaged] in study [in studio], and I have had many expenses just as others commonly have. Nevertheless, provided I had first composed a compendium, I am certain that I could directly teach a solicitous and confident man whatever I knew of those sciences and languages...