(1732 – 1815)
Scottish Minister and Writer



  • Ordained minister, M.A.


  • From 1755 to 1815 William Duff served as minister of several parishes in Aberdeenshire, Scotland.
  • He authored several publications, including Essays on Original Genius (1767), Critical Observations on the Writings of the Most Celebrated Original Geniuses in Poetry (1770), The History of Rhedi, the Hermit of Mount Ararat: An Oriental Tale (1773), Sermons on Several Occasions, (1786), Letters on the Intellectual and Moral Character of Women (1807) and The Last Address of a Clergyman in the Decline of Life. (1814).

Definition of Intelligence*

“The principal ingredients which constitute [genius] are imagination, judgment, and taste (Duff, 1767, p.6)”

“Genius is characterized by a copious and plastic, as well as a vivid and extensive imagination, by which means it is equally qualified to invent and create, or to conceive and describe in the most lively manner the objects it contemplates…On the other hand, wit and humor neither invent nor create; they neither possess the vigor, the compass, nor the plastic power of the other quality (Duff, 1767, p. 48).”

Major Contributions

  • His 1767 book An Essay on Original Genius was in fact (but not in name) a treatise on differential psychology.

Ideas and Interests

Duff’s 1767 volume, An Essay on Original Genius, was one of the earliest treatises on differential psychology. When Duff began his book he set out to explain the peculiar character of poetic talent, but as his work progressed he found that its subject had become larger in scope. He deferred to this new plan, and in the end he found that he had written a book about the nature and components of genius. His volume is divided into two parts. Book One defines genius and explains its origins. Book Two explores degrees of genius and discusses the ways in which genius manifests itself in specific scientific and artistic disciplines.

To Duff, the principal component of genius was imagination. In this respect, he did not differentiate between intelligence and creativity. He believed that humor and wit (the speed and liveliness with which ideas come) are also important parts of the intellect, but since they are not creative, they are subordinate to imagination (Duff, 1767, p. 48-49; Mahoney, 1964, p. viii).

it appears that wit and humour, though nearly allied to true genius, being the offspring of the same parent, are however of a distinct nature; since the former are produced by the efforts of a rambling and sportive fancy, the latter proceeds from the copious effusions of a plastic imagination. Hence it will follow, that every man of great wit will not be a great genius, or will every man of great genius be a great wit (Duff, 1767, p. 52-53).

According to Duff, true genius comes about when the individual has been endowed with an abundance of imagination, judgment and taste (Duff, 1767, p. 6, 64). Every person possesses these components in varying degrees, but only geniuses have the right combination of all three (Duff, 1767, p. 65-66). Imagination is foremost in importance:

Imagination is the faculty whereby the mind not only reflects on its own operations, but which assembles the various ideas conveyed to the understanding by the canal of sensations, and treasured up in the repository of the memory, compounding or disjoining them at pleasure; at which, by its plastic power of inventing new associations of ideas, and of combining them with infinite variety, is enabled to present a creation of its own, and to exhibit scenes and objects which never existed in nature. So indispensably necessary is this faculty in the composition of genius, that all the discoveries in science, and all the inventions and improvements in art, if we except such as have arisen from mere accident, derive their origin from its vigorous exertion (Duff, 1767, p. 6-7).

Without judgment, imagination is prone to create novel but useless creations. Judgment acts as the censor, and is therefore an indispensable factor in the creation of any great work:

[Judgment] is cool, attentive and considerate. It canvasses the design, ponders the sentiments, examines their propriety, and connection, and reviews the whole composition with severe impartiality. Thus it appears to be in every respect a proper counterbalance to the rambling and volatile power of imagination (Duff, 1767, p.9).

The third ingredient of genius is taste. Taste compliments judgment, but its role is aesthetic and emotional rather than cognitive. Although the faculty of judgment is useful for pointing out obvious defects in a work, its vision is crude; it cannot see beauty (Duff, 1767, p. 10). Duff asserted that taste is de rigueur in any creative process, but that it is particularly necessary in the Arts:

Taste…must be contented to act an inferior and subordinate part in the researches of science; it must not pretend to take the lead of reason, but humbly follow the path marked out by it. In the designs and works of art, the case is quite otherwise. Instead of being directed by judgment, it claims the direction in it s turn; its authority is uncontrollable,, and there lies no appeal from its decisions. Indeed it is well qualified to decide with precision and certainty on subjects of this kind (Duff, 1767, p. 12).

Duff explained that the interplay of these three components is the reason that genius is rarely observable in children. Imagination appears early, but judgment and taste require wisdom that can only come with maturity:

There are some persons, it is true, in whom a certain bias or talent for one particular art or science…appears in very early life; and in so great a degree as would incline us to imagine, that such a disposition and talent must have been congenial and innate. While persons are yet children, we discover in their infantile pursuits the opening buds of genius; we discern the rudiments of the philosopher, the poet, the painter, and the architect. The productions indeed of youthful geniuses will be naturally marked with those improprieties and defects, both in design, sentiment and expression, which result from the florid, exuberant, and undisciplined imagination, that is peculiar to an age wherein judgment hath not yet exerted its chastening power (Duff, 1767, p.30-31).

*Duff did not use the word “intelligence”.

Selected Publications

Duff, W. (1767/1964). An essay on original genius and its various modes of exertion in philosophy and the fine arts, particularly in poetry. Gainesville, FL: Scholars’ Facsimiles and Reprints.

Duff, W. (1770/1973). Critical observations on the writings of the most celebrated original geniuses in poetry. Delmar, NY: Scholars Facsimiles and Reprints.


Mahoney, J. (1964). Introduction. In J.L. Maloney (Ed.), An essay on Original Genius (pp. v-ix). Gainesville, FL: Scholars’ Facsimiles and Reprints.

Stephen, L., & Lee, S. (Eds.) (1949). Duff, William. In The dictionary of national biography (pp. 131-132). London: Oxford University Press.