By what Argument can it be prov'd, that the Perceptions of the Mind must be caus'd by external Objects, entirely different from, tho' resembling them (if that be possible) and could not arise either from the Energy of the Mind itself, or from the Suggestion of some invisible and unknown Spirit, or from some other Cause still more unknown to us? 'Tis acknowledg'd, that, in fact, many of these Perceptions arise not from any thing external, as in Dreams, Madness, and other Diseases. And nothing can be more inexplicable than the Manner, in which Body should so operate upon Mind as ever to convey an Image of itself to a Substance suppos'd of so different, and even contrary a Nature.
'Tis a Question of Fact, whether the Perceptions of the Senses be produc'd by external Objects, resembling them: How shall this Question be determin'd? By Experience surely, as all other Questions of a like Nature. But here Experience is, and must be entirely silent. The Mind has never any thing present to it but the Perceptions, and cannot possibly reach any Experience of their Connexion with Objects. The Supposition of such a Connexion is, therefore, without any Foundation in Reasoning.
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