A recent search of Google Books using the keywords "snail" and "Constantinople" produced several hits. One of them was Method in Almsgiving: A Handbook for Helpers, by Matthew Weston Moggridge, published in 1882. It had nothing to do either with snails or Constantinople, but featured this statement on p. 97:
Patience and a little cold-cream are said to have taken a snail to Constantinople...I suppose the implied meaning is that if a creature so slow as a snail can eventually reach Constantinople (but from where?), then a patient human being (with a little help from ointments and the like) will sooner or later accomplish what he/she set out to accomplish.
Then I got curious about the origin and the exact form of this proverb, if I may call it that. Was it patience and a little cold-cream have taken a snail to Constantinople or patience and a little cold-cream will take a snail to Constantinople or something else along those lines? And who said it and when?
Searching the Internet via Google using various combinations of “snail, Constantinople, cold cream, patience” or possible fragments such as “snail to Constantinople” did not produce anything even remotely relevant other than the cited book itself. Nevertheless, some noteworthy quotations featuring Constantinople and snails surfaced.
For example, this one from The sons of Erin; or, Modern sentiments by Alicia Le Fanu (1812):
Fitz. Yes, Madam, I have measured some ground;—France, Italy, Germany, Russia, Prussia—East and West Indies-—North and South America-—Newfoundland and the Cape of Good Hope—Botany Bay—Turkey, which I think the finest country in the world. Pray, Madam, were you ever tempted to go to Constantinople?Or this one from Victor Hugo’s Notre-Dame de Paris (The Hunchback of Notre Dame) (1831):
[Quasimodo’s] salient angles fitted, so to speak, into the retreating angles of the [Cathedral] till he seemed not its inhabitant, but its natural tenant. He might almost be said to have taken on its shape, as the snail does that of its shell.As for the pedigree of the saying about taking a snail to Constantinople, however, I am still in the dark. Pray, my readers, enlighten, if you can, me or Deniz over at The Girdle of Melian.