The solution of the problem,--What is it that causes this difference? has been often attempted, sometimes with partial, but never with complete, success. That most commonly given is the following:--The effect of association in old buildings,--the mellowing power of time,--the evident antiquity of surrounding objects,--the natural beauties of foliage, moss, and ivy, that require centuries to reach perfection;--as on the other hand, the bareness, the newness, nay even the sharpness and vigour of new work; these, it is said, are sufficient to stamp a different character on each. There is doubtless something in this; but that it is not the whole cause is evident from the fact, that give a modern church all the above mentioned advantages on paper, and an experienced eye will soon detect it to be modern. Those writers who, as Grose, Milner, and Carter, lived before the details of Christian art were understood, seem to have placed its perfection in a thorough knowledge of these: experience has proved them wrong. Others, as Mr. Petit, [Footnote 3] have made a kind of ideal picturesque; and, having exalted the phantasm into an idol, have fallen down and worshipped it. Others, again, have sought for an explanation of the difficulty in mathematical contrivance and mechanical ingenuity; and the result has been little more than the discovery of curious eave-drains, and wonderful cast-iron roof-work. Lastly, Mr. Pugin (_cum talis sis, utinain noster esses!_) has placed the thing required in _Reality_. {xxi} That is, to quote his own words, in making these the two great rules of design:-- 1. That there should be no features about a building which are not necessary for convenience, construction, or propriety: 2. That all ornament should consist of enrichment of the essential construction of a building.' [Footnote 4] And we may add, as a corollary, still quoting the same writer:--'The smallest detail should have a meaning or serve a purpose: the construction itself should vary with the material employed: and the designs should be adapted to the material in which they are to be executed.' Still, most true and most important as are these remarks, we must insist on one more axiom, otherwise Christian art will but mock us, and not show us wherein its great strength lieth. [Footnote 3: See the review of his work in the _Ecclesiologist_, vol. i, pp. 91-105.] [Footnote 4: Pugin's 'True Principles,' p. 1.] A Catholic architect must be a Catholic in heart. Simple knowledge will no more enable a man to build up God's material, than His spiritual temples. In ancient times, the finest buildings were designed by the holiest bishops. Wykeham and Poore will occur to every churchman. And we have every reason to believe, from God's Word, from Catholic consent, and even from philosophical principles, that such must always be the case.