In pursuance of the same principle, and on the authority of the Statutes--intervention on the part of the public authorities not being required--it was strictly forbidden, under penalty of a fine or of expulsion, to sell damaged meat, bad fish, rotten eggs,[37] or pigs which had been fed by a barber-surgeon who might have fattened them on the blood of sick people.[38] The dyers pledged themselves to use nothing but fast colours, furriers to use only skins which had not been previously used, mattress-makers never to employ wool coming from hospitals. The tailor who spoilt a garment or kept a piece of cloth entrusted to him was made to pay back his client and was punished by his fellows. In Maine a butcher might not display a piece of beef on his stall unless two witnesses could testify to having seen the animal brought in alive.[39] If by any chance an article passed through the hands of two craft guilds, delegates from each had to assure themselves that the rules of both had been faithfully observed.[40] The guild prided itself on letting nothing leave its shops but finished products, perfect of their kind; it examined and stamped every article, and further required that it should bear a special trade-mark stating where it was made and its just price.[41] At Ypres, towards the end of the thirteenth century, the pieces of cloth thus officially accepted numbered 8000 a year. Nor was this all; like Caesar's wife, the guild must be above suspicion; not only fraud, but the very appearance of fraud was rigorously excluded, all that might deceive the buyer was forbidden. In Florence jewellers might not use sham stones, even if they declared them to be such;[42] in Paris it was forbidden to make glass jewels in imitation of real stones, or to put a leaf of metal under an emerald to give it an artificial brilliance;[43] plated and lined goods were not allowed, as they might be mistaken for solid gold or silver.[44] Once when a goldsmith, thinking no harm, had made a bowl of this kind, it was decided, after deliberation, to sell it secretly, and he was cautioned never to make another. Sale was as carefully watched over as production. Not only had the weights and measures to be verified and controlled in conformity with carefully preserved standards, but at Florence, for instance, the "iron ruler" of the _Calimala_ was the standard for measuring woollen materials, and there were besides minute directions for measuring; there were prescribed methods for measuring a piece of cloth, or for filling a bushel with onions by placing the arms round the edge in order to add to the contents and ensure good measure.[45]