Mr. Gladstone, then Chancellor of the Exchequer, had interrupted him in a description of his work on electricity to put the impatient inquiry: 'But, after all, what use is it?' Like a flash of lightning came the response: 'Why, sir, there is every probability that you will soon be able to tax it!'
Michael Faraday, in James Kendall, Michael Faraday, Man of Simplicity, Introduction (1955), p. 14.