Attention should now be called to the popular element in the constitution. That the guilds were solidly established by the early part of the twelfth century is indubitably proved. Villani says that towards the year 1150 the Consuls of the Merchants, or rather of the "Calimala Guild," were entrusted by the Commune of Florence with the building works of "San Giovanni" (i. 60). Of still greater significance is the fact that on February 3, 1182, the men of Empoli, in making submission to Florence, were bound to make a yearly payment of fifty pounds of "good money" (_buoni denari_) to the Consuls or Rectors of the city, and, failing these officials, to the Consuls of the Merchants,[135] as representing the Commune. Now, if these Consuls had reached so high a degree of importance in 1182, we are entitled to believe that the guild was of no recent origin. And remembering that the guild in question was the Calimala--_i.e._, that of finishers and dyers of woollen cloths manufactured abroad, and more especially in Flanders, imported by Florence, and thence despatched to foreign markets--we shall understand that Florentine commerce must have already attained a prodigious development, and consequently that many of the guilds must have been already long established. A solitary instance would naturally afford little proof, since it might be open to various interpretations; but others can be adduced to the same effect. In a treaty between Lucca and Florence of July 21, 1184, we find a stipulation according to which the terms might be modified by the Florentine Consuls _comuni populo electi_, and by twenty-five counsellors, provided, as was expressly declared, the Consuls of the merchants were comprised in the number.[136] Likewise, when the men of Trebbio made submission on July 14, 1193, the power of incorporating the agreement in the City Statutes was exclusively reserved to the seven _Rectores qui sunt super Capitibus Artium_.[137]