In his third pause, he therefore arrives at that point in which the whole circle of human science is to be explained. Symbols, we know, are in themselves arbitrary and of conventional signification, and the complete circle of human science might have been as well symbolized by any other sign or series of doctrines as by the seven liberal arts and sciences. But Masonry is an institution of the olden time; and this selection of the liberal arts and sciences as a symbol of the completion of human learning is one of the most pregnant evidences that we have of its antiquity. In the seventh century, and for a long time afterwards, the circle of instruction to which all the learning of the most eminent schools and most distinguished philosophers was confined, was limited to what were then called the liberal arts and sciences, and consisted of two branches, the _trivium_ and the _quadrivium_.[154] The _trivium_ included grammar, rhetoric, and logic; the _quadrivium_ comprehended arithmetic, geometry, music, and astronomy. "These seven heads," says Enfield, "were supposed to include universal knowledge. He who was master of these was thought to have no need of a preceptor to explain any books or to solve any questions which lay within the compass of human reason, the knowledge of the _trivium_ having furnished him with the key to all language, and that of the _quadrivium_ having opened to him the secret laws of nature." [155] At a period, says the same writer, when few were instructed in the _trivium_, and very few studied the _quadrivium_, to be master of both was sufficient to complete the character of a philosopher. The propriety, therefore, of adopting the seven liberal arts and sciences as a symbol of the completion of human learning is apparent. The candidate, having reached this point, is now supposed to have accomplished the task upon which he had entered--he has reached the last step, and is now ready to receive the full fruition of human learning. So far, then, we are able to comprehend the true symbolism of the Winding Stairs. They represent the progress of an inquiring mind with the toils and labors of intellectual cultivation and study, and the preparatory acquisition of all human science, as a preliminary step to the attainment of divine truth, which it must be remembered is always symbolized in Masonry by the WORD.