After the earliest times quotations were indicated by ticks on the margin or by indented paragraphs. Sometimes the substance of the quotation was written in a smaller hand or otherwise distinguished from the body of the text. Scribes were by no means infallible and corrections are not uncommon. Erasures on papyrus were difficult, if not impossible, and therefore other means of correction had to be used. This is particularly the case because writing material was too expensive to be wasted and a copyist's mistake could not be permitted to spoil a roll of a papyrus or a sheet of vellum. In the case of vellum, however, if the mistake were immediately discovered the ink could be washed off with a sponge. If, however, the mistake were discovered only on revision after the ink had bitten into the vellum, it was necessary to use the knife and to restore the surface as well as possible by rubbing it with some smooth hard substance like the rubber shown in the illustration on page 13. Superfluous letters or words were sometimes removed by drawing a pen through them and sometimes removal was indicated by dots, or small marks, which might be over the letters, under them, or even in the open spaces of the letters themselves. Attempts were occasionally made to make one letter over into another to correct a mistake. Omitted passages or notes are inserted in the margin with some indication of the place where they should be read in the text. Abbreviations and contractions were very extensively used, partly to avoid labor and partly to save material. Phrases of frequent occurrence and perfectly well-known meaning were indicated simply by initials like the familiar S. P. Q. R., Senatus Populusque Romanus, the Roman Senate and People, or the s. s. a. b. s. m. used by Spaniards to close letters, meaning "your faithful servant who kisses your hands." Letters commonly occurring together were elided and abbreviated, as was done to a limited extent as late as the 18th century, at which period we see such abbreviations as yt=that. It may be interesting to note that y in this combination and the similar combination "ye," used as the article, is not the semi-vowel y but is the survival, or revival, of an Anglo-Saxon letter of very similar form called "thorn" and equivalent in value to th. In the "yt" then, we have the y or thorn substituted for th and the vowel elided, but the sign should be pronounced "that." The sign "ye" as in the familiar phrase of the posters "ye olde folkes' concerte," should always be pronounced "the" and never like the pronoun ye.