All popular and settled notions, however unfounded, like prejudices early imbibed, are with difficulty eradicated. Among these may be instanced the dictum of the astonishing rapidity of Thought, which is almost proverbial, and generally believed: even Mr. TOOKE, Vol. I., p. 28, conforms to this established maxim. "Words have been called _winged_: and they well deserve that name, when their abbreviations are compared with the progress which speech could make without these inventions; but when compared with the _rapidity_ of _thought_, they have not the smallest claim to that title." By calculation, the progress of light from the sun and other luminaries is said to be ascertained; and likewise the rate at which sound travels: but hitherto no contrivance has been fabricated to estimate the rapidity of thought. If the succession of our thoughts should be more rapid than they can be distinctly apprehended, confusion must ensue, and their rapidity would render them useless. Our perceptions are regulated by the same law. If the prismatic colours be painted on a surface which is revolved with great rapidity, the individual colours will not be apparent. The succession of sounds to a definite number, may be severally distinguished, in a certain interval: but if the succession be increased beyond the power of discrimination, they will impress the ear as one uniform sound. The same principle must regulate our thoughts, whether they be composed of Ideas or words, or, if it be possible, of both jumbled together. It does not appear that our thoughts for any useful purpose, which must imply their communication to others, or for a record in written characters, _can_ be more rapid than the intelligible pronunciation of the words themselves, and which, when delivered in quick succession, leave the short-hand-writer behind.[7] As Ideas can be nothing more than the mere phantasms attendant on visual perception, which, like the perceptions of the other senses, are commuted for words, that, by the aid of memory, recall in their absence the objects that have been perceived; it would be difficult to suppose that Ideas could fortuitously or voluntarily assemble in a more rapid succession, than the words for which they have been commuted, without producing confusion. It frequently happens to inexperienced persons, in giving evidence before a legal tribunal, or in addressing a popular assembly, that they cannot proceed; and they are generally disposed to interpret this failure, to their thoughts occurring in a succession too rapid for their utterance. Allowing the apology to be correct, it is a proof that such rapidity is inconvenient, and renders the Thought wholly useless if it cannot be communicated.