  Reid's aesthetics is composed of two core theses: that a work, to be an artwork, must express the artist's sentiments, and that aesthetic properties, like beauty and sublimity, are strictly speaking properties of the mind of the artist and not properties of material objects. Reid's mature aesthetics exemplifies a remarkable degree of sophistication for its time period. First, he possesses a clear concept of the fine arts and offers his readers a taxonomy of them (Kivy 2004). Second, Reid discusses the formal or structural properties of artworks in virtue of which they can be appraised in aesthetic terms. Third, Reid has a theoretical framework that unifies his concept of the fine arts and his account of how formal properties of objects make those objects works of art: Reid advocates an expression theory of art, arguably the first Western philosopher to do so.