*** w93 8/15 pp. 15-16 pars. 16-18 Go On Growing in Knowledge ***
16 As an illustration, consider permafrost, the permanently frozen ground in the Arctic and in other regions where the average temperature is below freezing. The soil, rocks, and groundwater freeze into a solid mass, sometimes to a depth of 3,000 feet [900 m]. In the summer, thawing may occur in the surface soil (called the active layer). However, this thin layer of thawed soil is usually muddy because moisture cannot drain into the permafrost below. Plants that grow in the thin top layer are often small or stunted; their roots cannot penetrate the permafrost. ‘What,' you may wonder, ‘does permafrost have to do with whether I am growing in knowledge of Bible truth?'
17 Permafrost well illustrates the situation of one whose mental powers are not actively involved with taking in, remembering, and using accurate knowledge. (Compare Matthew 13:5, 20, 21.) The person likely has the mental capacity to learn various subjects, including Bible truth. He studied "the elementary things of the sacred pronouncements of God" and may have qualified to be baptized, as did those Hebrew Christians. He might, though, not "press on to maturity," to things beyond "the primary doctrine about the Christ."-Hebrews 5:12; 6:1.
18 Visualize some of those Christians at meetings back then. They were present and awake, but were their minds involved in learning? Were they actively and earnestly growing in knowledge? Perhaps not. For the immature ones, any involvement in meetings took place in a thin active layer, as it were, while below was a frozen depth. The roots of more solid or complicated truths could not penetrate into this region of mental permafrost.-Compare Isaiah 40:24.