You must not tell a lie, or "match" old work, joining your own on to it as if itself were old.
Shall we work in the style of the "New art," then—"l'art Nouveau"? the style of the last new poster? the art-tree, the art-bird, the art-squirm, and the ace of spades form of ornament?
Heaven in mercy defend us and forbid it!
Canopies are venerable; thirteenth-century panels and borders are venerable, t
he great traditional vestments are so, and liturgy, and symbolism, and ceremony. These are not things of one age alone, but belong to all time. Get, wherever possible, authority on all these points.
Must we work in a "style," then—a "Gothic" style?
No.
What rule, then?
It is hard to formulate so as to cover all questions, but something thus:—
Take forms, and proportions, and scale from the style of the church you are to work in.