In her church work she continued to find the little distraction from toil which gave life its savour. She began to attend the Sabbath Morning Fellowship and week-night prayer meetings. She also taught a class of "lovable lassies" in the Sabbath School—"I had the impudence of ignorance then in special degree surely" was her mature comment on this—and became a distributor of the Monthly Visitor. Despite the weary hours in the factory, and a long walk to and from the church, she was never absent from any of the services or meetings. "We would as soon have thought of going to the moon as of being absent from a service," she wrote shortly before she died. "And we throve very well on it too. How often, when lying awake at night, my time for thinking, do I go back to those wonderful days!"

She owed much to her association with the Church, but more to her Bible. Once a girl asked her for something to read, and she handed her the Book saying, "Take that; it has made me a changed lassie." The study of it was less a duty than a joy; it was like reading a message addressed specially to herself, containing news of surpassing personal interest and import. God was very real to her. To think that behind all the strain and struggle and show of the world there was a Personality, not a thought or a dream, not something she could not tell what, in spaces she knew not where, but One who was actual and close to her, overflowing with love and compassion, and ready to listen to her, and to heal and guide and strengthen her—it was marvellous. She wished to know all He had to tell her, in order that she might rule her conduct according to His will. Most of all it was the story of Christ that she pored over and thought about. His Divine majesty, the beauty and grace of His life, the pathos of His death on the Cross, affected her inexpressibly. But it was His love, so strong, so tender, so pitiful, that won her heart and devotion and filled her with a happiness and peace that suffused her inner life like sunshine. In return she loved Him with a love so intense that it was often a pain. She felt that she could not do enough for one who had done so much for her. As the years passed she surrendered herself more and more to His influence, and was ready for any duty she was called upon to do for Him, no matter how humble or exacting it might be. It was this passion of love and gratitude, this abandonment of self, this longing for service, that carried her into her life-work.

Wishart Church stood in the midst of slums. Pends, or arched passages, led from the Cowgate into tall tenements with outside spiral stairs which opened upon a maze of landings and homes. Out of these sunless rookeries tides of young life poured by night and day, and spread over the neighbouring streets in undisciplined freedom. Mary's heart often ached for these boys and girls, whom she loved in spite of all their roughness; and when a mission was determined on, and a room was taken at 6 Queen Street—a small side thoroughfare nearly opposite Quarry Pend, one of the worst of the alleys—she volunteered as a teacher. And so began a second period of stem training which was to serve her well in the years to come. The wilder spirits made sport of the meetings and endeavoured to wreck them. "That little room," she wrote, "was full of romantic experiences." There was danger outside when the staff separated, and she recalled how several of the older men surrounded the "smaller individuals" when they faced the storm. One of these was Mr. J. H. Smith, who became her warm friend and counsellor.

As the mission developed, a shop under the church at the side of Wishart Pend was taken and the meetings transferred to it, she having charge of classes for boys and girls both on Sundays and week-nights. Open-air work was at that time dangerous, but she and a few others attempted it: they were opposed by roughs and pelted with mud. There was one gang that was resolved to break up the mission with which she had come to be identified. One night they closed in about her on the street. The leader carried a leaden weight at the end of a piece of cord, and swung it threateningly round her head. She stood her ground. Nearer and nearer the missile came. It shaved her brow. She never winced. The weight crashed to the ground. "She's game, boys," he exclaimed. To show their appreciation of her spirit they went in a body to the meeting. There her bright eyes, her sympathy, and her firmness shaped them into order and attention….

On the wall of one of her bush houses in West Africa there used to hang a photograph of a man and his wife and family. The man was the lad who had swung the lead. On attaining a good position he had sent her the photograph in grateful remembrance of what had been the turning-point in his life….

Another lad, a bully, used to stand outside the hall with a whip in hand driving the young fellows into "Mary Slessor's meeting," but refusing to go in himself. One day the girl weaver faced him. "If we changed places what would happen?" she asked, and he replied, "I would get this whip across my back." She turned her back. "I'll bear it for you if you'll go in," she said. "Would you really bear that for me?" "Yes, and far more—go on, I mean it." He threw down the whip and followed her in, and gave himself the same day to Christ. Even then she was unconventional in her methods and was criticised for it. She had a passion for the countryside, and often on Saturday afternoons she would take her class of lads away out to the green fields, regardless of social canons.

By and by a new field of work was opened up when a number of progressive minds in the city formed Victoria Street United Presbyterian congregation, not far from her familiar haunts. In connection with the movement a mission service for the young was started on Sunday mornings under the presidency of Mr. James Logic, of Tay Square Church, and to him Mary offered her services as a monitor. Mr. Logie soon noticed the capacity of the young assistant and won her confidence and regard. Like most people she was unconscious at the moment of the unseen forces moulding her life, but she came in after days to realise the wise ordering of this friendship. Mr. Logie became interested in her work and ideals, and sought to promote her interests in every way. She came to trust Mm implicitly—"He is the best earthly friend I have," she wrote-and he guided her thenceforward in all her money affairs.

She was as successful with the lads at this service as she had been elsewhere. Before the meeting she would flit through the dark passages in the tenements and knock, and rouse them up from sleep, and plead with them to turn out to it. Her influence over them was extraordinary, They adored her and gave her shy allegiance, and the result was seen in changed habits and transformed lives. It was the same in the houses she visited. She went there not as one who was superior to the inmates, but as one of themselves. In the most natural way she would sit down by the fire and nurse a child, or take a cup of tea at the table. Her sympathy, her delicate tact, her cheery counsel won many a woman's heart and braced her for higher endeavour. It was the same in the factory; her influence told on the workers about her; some she strengthened, others she won over to Christ, and these created an atmosphere which was felt throughout the building.

And yet what was she? Only a working girl, plain in appearance and in dress, diffident and self-effacing. "But," says one whom she used to take down as a boy to the mission and place beside her as she taught, "she possessed something we could not grasp, something indefinable." It was the glow of the spirit of Christ which lit up her inner life and shone in her face, and which, unknown even to herself, was then and afterwards the source of her distinction and her power.