In the ardor and assiduity of his devotion to the colonial cause Otis had overtaxed his mental powers. His fine faculties that had been exerted so strenuously, and with such striking effect, in the service of his country, were sinking under the excitement and the effort which had sustained them in the heat of action. For ten years he had abandoned the ordinary practice of his profession and renouncing all recreation had given his entire time and thought, himself, verily, to the "great argument" which involved the welfare of the Colonies, and as we now see it, of the world. To allow one idea exclusive occupancy of the mind and constantly to ponder a single topic, is a very frequent and almost sure cause of mental distress. It was his highest merit and at the same time his greatest misfortune, that Otis permitted this political controversy to have such an absorbing and despotic command of his attention that melancholy consequences gradually appeared and left little hope of his final restoration. His excitable and passionate temperament allowed the fire to be soon kindled, and nourished the flame in which his intellect, strong as it had been, was ultimately destroyed. Otis's mental malady first appeared in a form which was mistaken for mere eccentricity of humor, and some time elapsed before his oddities of fancy and conduct deepened into acknowledged insanity. An incident which might have aroused the suspicions of his friends occurred during the legislative session of 1769, when at the close of a powerful and ingenious speech by Brigadier Ruggles in which he had made a deep impression, Otis at once arose and in an impassioned tone and manner which struck awe upon all those present, exclaimed, "Mr. Speaker, the liberty of this country is gone forever, and I'll go after it;" and turning round immediately left the House. Some members stared, some laughed, but none seemed to suspect the true cause of this odd behavior.