“Beauty is a Harmony of Objects, begetting Pleasure by the Eye. There are two Causes of Beauty--natural and customary. Natural is from Geometry, consisting in Uniformity (that is equality) and Proportion. Customary Beauty is begotten by the Use of our Senses to those Objects which are usually pleasing to us for other Causes, as Familiarity or particular Inclination breeds a Love to Things not in themselves lovely. Here lies the great Occasion of Errors, here is tried the Architects Judgment, but always the true Test is natural or geometrical Beauty. Geometrical Figures are naturally more beautiful than other irregular; in this all consent as to a Law of Nature. Of geometrical Figures, the Square and the Circle are most beautiful; next the Parallelogram and the Oval. Straight Lines are more beautiful than Curve.... There are only two beautiful Positions of strait Lines, perpendicular and horizontal; this is from Nature and consequently Necessity, no other than upright being firm.” Wren’s acute judgment noted the great part played by such factors as historical association, one of the “other causes,” in the public appreciation of architecture. Earlier in the Tract he makes obeisance to the three principles which had been laid down by earlier writers, but with a characteristic rider: “Beauty, Firmness and Convenience are the Principles: the two first depend upon geometrical Reasons of Opticks and Staticks; the third only makes the Variety.” Scholarly though Wren was in his art, he took nothing for granted, but examined the common-places with a desire to establish reasons for them or reject them: “Modern authors who have treated of Architecture seem generally to have little more in view, but to set down the Proportions of Columns, Architraves and Cornices in the several Orders, as they are distinguished into Dorick, Ionick, Corinthian, and Composite, and in these Proportions finding them in the ancient Fabricks of the Greeks and Romans (though more arbitrarily used than they care to acknowledge) they have reduced them into Rules, too strict and pedantick, and so as not to be transgressed, without the Crime of Barbarity, though in their own Nature they are but the Modes and Fashions of those ages wherein they were used.” There is a very modern ring about the following moralising: “Although Architecture contains many excellent Parts, besides the ranging of Pillars, yet Curiosity may lead us to consider whence this Affectation arose originally, so as to judge nothing beautiful but what was adorned with Columns, even where there was no real use of them.... It will be to the purpose, therefore, to examine whence proceeded this Affectation of a Mode which hath continued now at least 3,000 years, and the rather, because it may lead us to the Grounds of Architecture and by what Steps this Humour of Colonades came into Practice in all Ages.”