It was impossible for Simpson to enter into any movement without taking a prominent part in it. That Christmas Day on which all doubts left him was followed by days of extraordinarily zealous work, such as would have been expected of him after he had convinced himself that he had a mission to spread abroad this, the latest, and, in his opinion, the greatest, of his discoveries. He plunged at once into the midst of Evangelical societies, missions, and prayer-meetings, amongst the upper and lower classes of Edinburgh, and made excursions into the mining districts of his native county to deliver addresses. He interested himself in the education of theological students, and in foreign missions, and added to his literary work the writing of religious addresses, tracts and hymns. His example had a powerful influence in Edinburgh. It is said that he frequently addressed on a Sunday evening Evangelical assemblies of two thousand persons. The news of his so-called conversion was gleefully spread by well-meaning folks, who had given credence to statements published by his enemies, and imagined that here was a bad if a great man turned aside from the broad to the narrow path. This enthusiastic revival movement died down in time, and Simpson returned to his ordinary everyday life. More sorrow soon fell to his lot. In 1862 his fifth child, James, who had always been an invalid, was taken from him at the age of fifteen. In 1866 the sad death of Dr. David Simpson, the eldest son, which has already been referred to, was followed in about a month's time by that of the eldest surviving daughter, Jessie, at the age of seventeen. The death of James, a sweet-natured child, stimulated him in the revival work. Pious friends had surrounded the little sufferer and led him to add his innocent influence in exciting his father's religious emotions. There is reason to believe that Simpson perceived much insincerity in the revival movement, and attempted to dissociate himself from active participation in it, on account of finding it impossible to work in harmony with some who, though loud in profession, flagrantly failed in practice.