Whatever intelligence man imparts to man, at least all beyond the crudest rudimentary beginnings, must be conveyed by conventions. There must have been an agreement, tacit or explicit, that a certain sign shall stand for a certain idea; and when that idea is to be expressed, this sign must be used. In order that the meaning of any communication may be understood, it is essential that the means of expression be appreciated by hearer as well as by speaker. We have agreed that in English a given sound shall represent a given idea; and to one who knows this tongue the specified sound, either spoken or suggested by letters, calls that idea up. To one unacquainted with English, the sound is meaningless, because he is not a party to the agreement which has fixed for it a conventional significance; or it may awake in his thought an idea entirely different, because he belongs to a nation where tacit agreement has fixed upon another meaning. The word "dot," for instance, has by English-speaking folk been appropriated to the notion of a trifling point or mark; while those who speak French, writing and pronouncing the word in the same way, take it to indicate a dowry. In order to communicate with any man, it is necessary to know what is the set of conventions with which he is accustomed to convey and to receive ideas. The principle holds also in art. There is a conventional language in sound or color or form as there is in words. It is broader as a rule, because oftener founded upon general human characteristics, because more directly and obviously borrowed from nature, and because not so warped and distorted by those concessions to utility which have modified the common tongues of men. Indeed, it might at first thought seem that the language of art is universal, but a little reflection will show that this is not the case. The sculpture of the Aztecs, for instance, is in an art language utterly different from that of the sculpture of the Greeks. If you recall the elaborately intricate uncouthness of the gods of old Yucatan, you will easily appreciate that the artists who shaped these did not employ the same artistic conventions as did the sculptors who breathed life into the Venus of Melos, or who embodied divine serenity and beauty in the Elgin marbles. To the Greeks those twisted and thick-lipped Aztec deities, clutching one another by their crests of plumes, or grasping rudely at one another's arms, would have conveyed no sentiment of beauty or of reverence; while it is equally to be supposed that the Aztec would have remained hardly moved before the wonders of Greek sculpture. The Hellenic art conventions, it is true, were more directly founded upon nature, and therefore more readily understood; but even this would not have overcome the fact that one nation had one art language and the other another. Those of you who were at the Columbian Exposition will remember how the music in the Midway Plaisance illustrated this same point.