It is not sufficient to study Torah. An individual must constantly review his Torah studies, so that they remain in his mind and becoame integrated into his personality. Indeed, the Sifri ascribes to this pasuk the admonition to repeat again and again that which we have learned. The Torah warns that, just as one has to be careful not to lose any penny that he has earned, he should likewise vigilantly guard against losing any Torah knowledge which he has acquired. In Iyov 28:7, Torah knowledge is compared to both gold and glass. Like gold, it is difficult to acquire, while like glass, it is easy to drop and lose.
We may suggest another reason for the analogy to glass. When glass falls and breaks, it splinters into sharp jagged pieces which are dangerous to anyone who touches them. Similarly, coming in contact with one who, due to a lack of dedication, has forgotten various aspects of his Torah wisdom is hazardous to one’s spiritual health. Torah is not a secular subject which is studied merely to be remembered. Rather, it represents the lifeblood of our people and must be constantly reviewed, so that its students become thoroughly imbued in its value.
