Though one of the most successful engineers of his age, Brindley was so illiterate as to be scarcely able to read or to write. By his unrivalled powers of abstraction and memory, he often executed his plans without committing them to paper; and when he was engaged in any difficult or complex undertaking, he was in the habit of retiring to bed, where he often remained for two or three days, till he had thoroughly completed his design. So singular, indeed, was the structure of his mind, that the spectacle of a play in London, disturbed to such a degree the balance of its mechanism, that he could not, for some time, resume his usual pursuits.