From practical science to mental philosophy; from electricity in the wire to electricity in the nerve; from Watts to Mesmer, from Mesmer to Reichenbach, from Reichenbach to Swedenborg, Spinoza, Condillac, Descartes, Berkeley, Aristotle, Plato, and the Magi and mystics of the East, were transitions which, however bewildering in their variety and scope, seemed easy and harmonious upon his lips as sequences in music. By-and-by – I forget now by what link of conjecture or illustration – he passed on to that field which lies beyond the boundary line of even conjectural philosophy, and reaches no man knows whither. He spoke of the soul and its aspirations; of the spirit and its powers; of second sight; of prophecy; of those phenomena which, under the names of ghosts, spectres, and supernatural appearances, have been denied by the sceptics and attested by the credulous, of all ages.