But why dwell upon particular instances? If any advocate of free-agency had really believed, that the passions, desires, affections, &c., exert no influence over the will, is it not certain that he would have availed himself of this principle? If the principle that no desire, or affection, or passion, is possessed of any power or causal influence, had been adopted by the advocates of free-agency, its bearing in favour of their cause would have been too obvious and too important to have been overlooked. The necessitarian might have supposed, if he had pleased, that our desires and affections are produced by the action of external objects; and yet, on the supposition that these exerted no positive or causal influence, the doctrine of liberty might have been most successfully maintained. For, after all, the desires and affections thus produced in the mind, would not, on the supposition in question, be the causes of our volitions. They would merely be the occasions on which we act. There would be no necessary connexion between what are called motives and their corresponding actions. Our desires or emotions might be under the influence and dominion of external causes, or of causes that are partly external and partly internal; but yet our volitions would be perfectly free from all preceding influences whatever. Our volitions might depend on certain conditions, it is true, such as the possession of certain desires or affections; but they would not result from the influence or action of them. They would be absolutely free and uncontrolled. The reason why this principle has not been employed by the advocates of free-agency is, I humbly conceive, because it has not been entertained by them. In short, if the advocates of free-agency had shaken off the common illusion that there is a real efficiency, or causal influence, exerted by the desires of the soul, they would have made it known in the most explicit and unequivocal terms. Instead of resorting to the expedients they have adopted, in order to surmount the difficulties by which they have been surrounded, they would, every where and on all occasions, have reminded their adversaries that those difficulties arise merely from ascribing a literal signification to language, which is only true in a metaphorical sense; and we should have had pages, not to say volumes, concerning this use of language, where we have not had a syllable. If the illusion in question has been as general as I have supposed, it is not difficult to account for its prevalence. The fact that a desire, or affection is the indispensable condition, the invariable antecedent, of an act of the will, is of itself sufficient to account for the prevalence of such a notion. Nothing is more common than for men to mistake an invariable antecedent for an efficient cause. This source of error, it is well known, has given rise to some of the most obstinate delusions that have ever infested and enslaved the human mind.