Before he had completed his education, his father abandoned the profession of teaching for that of a lawyer, and young Brady entered his office as office-boy and student, it being his desire to become an advocate. He was bright, quick-witted, and remarkably apt in his studies. His buoyant spirits and ready repartee often led him into encounters with his elders, who were generally forced to confess that his tongue was too much for them. His father encouraged him to form his own opinions, and to hold them tenaciously until convinced of his error. He made rapid progress in his legal studies, and soon acquired such proficiency in the management of the details of the office business that every thing which did not absolutely need his father's personal attention was left to him.
Although fond of social enjoyment, and full of the fire and joyfulness of youth, he knew how to seclude himself from the pleasures he relished so much. He was a hard and faithful student, allowing nothing to draw him from his books when he meant to devote himself to them. He read not only law, but history, poetry, biography, romance, in short, every thing that could store his mind with useful knowledge or add to its natural graces. He slept at the office, and often sat up the entire night engaged in study. Abbott speaks as follows of the early studies of Napoleon II., and it requires no straining of language or ideas to apply his remarks to this portion of the life of James T. Brady: "So great was his ardor for intellectual improvement that he considered every day as lost in which he had not made perceptible progress in knowledge. By this rigid mental discipline he acquired that wonderful power of concentration by which he was ever enabled to simplify subjects the most difficult and complicated." Mr. Brady, senior, was very proud of the energy and talent displayed by his son, and when the latter was nineteen years old the father said to a friend who had been speaking to him of the promise of the boy: "Yes, sir; he is a boy of great promise, a boy of splendid intellect and noble character. Young as he is, I regard him as a walking encyclopoedia; his mind seems to gild every subject it touches."