Yes, a Brother can leave the lodge before a meeting is completed, but he must do so with proper Masonic etiquette. It is important that he salutes the Worshipful Master at the Altar before he departs. This should be done in a respectful manner, avoiding any disturbance during rituals or when the Master is engaged in other duties. By following these guidelines, a Brother can leave the lodge while respecting the proceedings and the other members of the lodge.