Hell's Best Kept Secret, by Ray Comfort (Bellflower, CA: Ray Comfort, 1989), pp. 160-161.
Let me tell you a true but tragic story: A woman was once walking along a riverbank with her child. Suddenly the child slipped into the river. The mother screamed in terror. She couldn't swim, and besides, she was in the latter stages of pregnancy. Finally, somebody heard her screaming and rushed down to the riverbank. The utter tragedy was, when they stepped into those murky waters to retrieve that now dead child, they found that the water was only waist deep! That mother could have easily saved her child but didn't because of a lack of knowledge.