There are people who try to learn Torah, and when they see they don’t remember what they learned they give up altogether. Our Sages compared this to a king who gave his servant a bucket and promised him a golden coin for every bucket he fills with water. When he started filling it, he found there was a hole in the bucket and the water was spilling out, so he stopped. A wise person saw him and asked him why he stopped, and he explained that his energies were wasted for naught. The wise man retorted that surely the king knew the bucket had a hole and wanted to pay him not for the water but for his efforts. Similarly, Hashem surely knows our capabilities and knows that we do not remember everything we learn, yet he commanded us to learn to the best of our abilities, despite the ‘hole’ in our bucket, and told us that we would get much more than a gold coin for every word of Torah we utter. Hashem wants to give us reward for our efforts, so a person should not give up, but renew his efforts with vigor.
כ״ה בניסן ה׳תש״פ
"והאמת בלתי שום ספק כלל, שאם היה העולם כולו מקצה עד קצהו פנוי חס ושלום אף רגע אחד ממש מהעסק והתבוננות שלנו בתורה, כרגע היו נחרבים כל העולמות, עליונים ותחתונים, והיו לאפס ותוהו חס ושלום". (נפש החיים) 1