He was made principal of the Marischal College in 1759. This preferment lie owed to the patronage of the Duke of Argyle, (then the minister for Scotland,) to whom he applied for it by letter, and who, in considera tion of his relation to that noble family, as well as of his acknowledged merits, procured the situation for him in preference to other two candidates of no inconsiderable pretensions. Hitherto he had published nothing but a sermon preached before the synod of Aberdeen in 1752, on the character of a minister, as a teacher and pattern : and he himself thought so little of it, as to exclude it from the collection of sermons which he made a short time before his death. In 1760, he was appointed to preach a second time before the synod of Aberdeen, and on that occasion he delivered a discourse on miracles. This he was requested to publish, and he agreed to do so after having moulded it into the form of a disserta tion. As his object was to controvert the unsound and dangerous positions of Mr Hume, he bestowed the greatest care on this performance. He submitted the manuscript first to the Rev. Dr Blair in Edinburgh, and then to Mr Hume himself. By these gentlemen, one of whom was his friend and the other his opponent, he was favoured with various remarks, of which he very can didiy took advantage, for the purpose of improving his work. Mr Hume complained that in some cases he had used harsh expressions, pointed out certain misappre hensions of his meaning, and stated objections to what Mr Campbell had advanced. Mr Campbell, with the modesty and ingenuousness which distinguished him, removed what had given offence, either by its real or apparent severity, and at the same time introduced such additional arguments and illustrations as were suggested by the observations of Mr Hume. Having thus cor rected his treatise, he gave it to the public in 1763, pre vious to which time he had received, without any solici tation on his part, the degree of doctor in divinity from Kit g's College in Old Aberdeen. The Dissertation on Miracles is a work of great ability. The author shews a perfect acquaintance with his subject, detects the sophistry of Mr Hume with much sagacity, exposes all the equivocations of his language, and, in the course of a few pages, overturns the whole fabric of infidelity which that plausible metaphysician had raised, by de monstrating the fallacy of that hypothesis on which it had been built. Indeed a more masterly or conclusive per formance can scarcely be conceived ; and, without under valuing the works of Mr Adams and Bishop Douglas, both of which are excellent, it may be safely asserted, that a careful perusal of Dr Campbell's Dissertation alone, is sufficient to do away all the effect of Mr Hume's reasonings on the subject of miracles. Mr Hume him self was much pleased with it, as he declared, in a private letter which he addressed to the author ; and though lie did not confess that it was victorious, he yet praised it for the learning and ingenuity which it displayed, and for the civil and obliging manner in which the Doctor had conducted such an interesting dispute. At the same time it should not be overlooked, that he continued to publish his Essay on Miracles unaltered, and unexplain ed, and undefended, sheltering himself, no doubt, under the convenient resolution of never noticing any answers to his writings that might appear, but certainly acting, in this respect, without any of that candid and enlightened regard for truth by which, as a philosopher, he ought to have been actuated. The Dissertation was very favour ably received by all who took an interest in those dis quisitions which it embraced, and was particularly ac ceptable to the religious world, who saw it) it a com plete antidote to the poison circulated by INIr Hume, and in its author a champion for the troth, from whom still greater efforts might yet be expected. It was also soon translated into the French, Dutch, and German languages ; and from this time Dr Campbell's name was honoured and respected among all the learned men in Europe.
The twelve years during which he held the offices of principal of Marischul College, and one of the ministers of Aberdeen, were employed by him in a diligent dis charge of his professional duties, and in such other studies as his inclination led him to cultivate. Ile be
came a proficient in the science of Botany, which he afterwards found useful in the critical illustration of scripture. He improved his acquaintance with the Greek and Latin. lie acquired a competent knowledge of the Hebrew. lie made himself so far master of French and Italian as to become a critic in these lan guages. And be made considerable progress in the composition and revision of his work on the Philosophy of Rhetoric.
In 1771 the town council of Aberdeen appointed him professor of divinity in Marischal College, in conse quence of which he resigned his situation as one of the ministers of the city, though he was still under the necessity of preaching once every Lord's day in one of the established churches. In his new capacity he made great exertions to be useful. lie even did more, in the way of lecturing on theology, than the ordinary rules of his office prescribed; and introduced several improve ments into the mode of teaching his class, which showed the soundness of his own judgment, and the zeal with which he laboured for the advancement of his pupils. The same year in which he was raised to the divinity chair, he published a Sermon which he had preached be fore the synod of Aberdeen, entitled, The Spirit of the Gospel, neither a Spirit of Superstition nor of Enthu siasnz. This sermon, which abounds in enlightened views and liberal sentiments, was violently attacked both by Nonjurors and Methodists ; but the author did not observe any thing in these attacks sufficiently important or interesting to provoke a reply. He maintained a dignified, not a contemptuous, silence ; and his discourse, from its obvious and intrinsic superiority, has survived all the clamours that were raised against it by weak or furious bigots.
In 1776, Dr Campbell published his Philosophy of Rhetoric, in 2 viols 8vo : a work on which he had be stowed the labour of many years, and which reflects the highest honour on his intellectual character. It affords a display of grammatical skill, critical acumen, dis criminating taste, and philosophical talent, of which there arc but few examples in the republic of letters. Throughout the whole work we discover traces of a superior mind. Those passages are particularly worthy of perusing, in which the author treats of abstraction, on which subject he differs from Dr Reid ; of the cause of that pleasure which is derived from the representation of distressing scenes ; of the nature and use of verbal criticism ; and of the different sources of evidence, which is perhaps the most valuable portion of the performance, and is certainly equal to any thing which has yet al) .
geared upon the subject. The style of this production, like the style of all his productions, i3 simple, perspi cuous, and precise.
During the same year he preached on the national fast day, a Sermon on the nature, extent, and importance cf the duty rf In this sermon he endeavours to spew, that the Americans had no right, either front rya son or from scripture, to throw off their allegiance to the lIritish government. But though he reasons with his usual acuteness, it is not with his usual success. There are certain great principles which operate irre sistibly on the feelings of a people suffering from op pression, and struggling for liberty, though they may not very readily occur to an orator in the pulpit of an estab fished church ; and it is by overlooking these, that the Doctor has so easily arrived at his conclusion. It mat be remarked, that while he denies the right of the Americans to assert their independence, Inc very plainly hints the expediency of having granted it to them from the very beginning. Our government, labouring under a strange infatuation, were neither so just as to admi the claims of right, nor so wise as to yield to the dictates of expediency ; and at length they were brought under the imperious necessity of surrendering what they had hitherto withheld ; nor is there any reason to think that this event was delayed by Dr Campbell's sermon, al though, at the desire of Dean Tucker, with whom the doctor carried on a correspondence, 6000 copies of it were published and industriously circulated in America. to persuade the people there to resume their political chains.