Donaldson's thoughts in this work are part of a philosophical tradition connecting taste with moral excellence, under the heading of "sensibility."
An original delicacy of taste is also the inseparable effect and symptom of the true sensibility; which includes not only a sense of love, pity, gratitude, or common duty, for of those even the rudest natures are seldom altogether destitute; but it is a certain elegance of soul, which renders kindness most kind, and pleasure most pleasing; it is a genius and taste, the tenderness of friendship, the politeness of esteem, and the exquisite and refined endearments of love!(82-3)
All ignorance of beauty, or depravity of taste, is defective animation; all improvement and perfection of these, is increased sensibility; the powers of the mind, as well as of the body, being rendered more perfect by a proper exercise of them.(84)
Thus the natures with the highest sensibilities are at once the most moral, the most aesthetically discerning, and the most alive.