Robert Levet (1705–1782), a Yorkshireman who became a Parisian waiter, then garnered some training as an apothecary and moved to London, was eulogised by the poet Samuel Johnson, with whom Levet shared a friendship of thirty-six years, in Johnson's poem "On the Death of Dr. Robert Levet." Using only the above description and what you know about the world, "Samuel Johnson met Robert Levet in the 1750's." is definitely correct, incorrect, or inconclusive? 