General Discussion

It's a trick that is said to have been used on the Pharos of Alexandria by Sostratus, the architect.

"He [Sostratus] built the tower on Pharos, the mightiest and most beautiful work of all, that a beacon-light might shine from it for sailors far over the sea and that they might not be driven on to Paraetonia, said to be a very-difficult coast with no escape if you hit the reefs. After he had built the work he wrote his name on the masonry inside, covered it with gypsum, and having hidden it inscribed the name of the reigning king. He knew, as actually happened, that in a very short time the letters would fall away with the plaster and there would be revealed: 'Sostratus of Cnidos, the son of Dexiphanes, to the Divine Saviours, for the sake of them that sail at sea.' Thus, not even he had regard for the immediate moment or his own brief life-time: he looked to our day and eternity, as long as the tower shall stand and his skill abide. History then should be written in that spirit, with truthfulness and an eye to future expectations rather than with adulation and a view to the pleasure of present praise" (How to Write History, LXII).