Le mur murant Paris rend Paris murmurant.
The wall surrounding Paris is making Paris grumble.
Parisian saying after the Farmers-General of taxes, acting on a proposal by Lavoisier, erected a customs wall around Paris.

On entering his room, I was astonished and delighted to find that it was turned into a museum. The walls were festooned with all kinds of birds’ eggs, carefully blown out and strung on a thread. The chimney-piece was covered with stuffed squirrels, raccoons, and opossums; and the shelves around were likewise crowded with specimens, among which were fishes, frogs, snakes, lizards, and other reptiles. Besides these stuffed varieties, many paintings were arrayed on the walls, chiefly of birds.

To speculate without facts is to attempt to enter a house of which one has not the key, by wandering aimlessly round and round, searching the walls and now and then peeping through the windows. Facts are the key.