Lord John Russell (c. 1850) observed poetically that a "proverb is the wit of one, and the wisdom of many." But giving the word "proverb" the sort of definition theorists need has proven to be a difficult task, and although scholars often quote Archer Taylor's argument that formulating a scientific "definition of a proverb is too difficult to repay the undertaking... An incommunicable quality tells us this sentence is proverbial and that one is not. Hence no definition will enable us to identify positively a sentence as proverbial," many students of proverbs have attempted to itemize their essential characteristics.