Extracted from ''Letters of Fire'' by Rabbi M. Glazerson
The Torah has a revealed [nigleh] and a hidden [nistar] aspect. One who looks at it in a superficial manner deals only with the revealed aspect. However, if one deeply contemplates the Divinely-given Torah, one begins to discover the secrets hidden beneath the revealed aspect.
The root סכה can mean either ''to cover'' or ''to see''. In his works Kad Ha-Kemach and Sidduro shel Shabbat, Rabbeinu Bachyei mentions the dual meaning of the root סכה, and relates it to a verse in Mishlei: ''An utterance spoken in the right context is like golden apples in silver coverings''. The word for coverings is maskiot, which comes from the root שׁכה. Since the letters שׁ and ס are interchangeable this root is equivalent to סכה. The silver coverings, says Rabbeinu Bachyei, have small holes in them, through which one can see סכה the golden apples within.
The ''golden apples'' within the coverings symbolize the secrets of the Torah, while the ''silver coverings'' symbolize the revealed aspect. Only by means of the ''coverings'' - the revealed Torah - can man glimpse the ''golden apples'' within; for the secrets of the Torah are deeper than the ocean and wider than all the world, and man's intellect would not be able to grasp them at all without the aid of the revealed Torah.
Thus the covering - סכה - is what makes the seeing - סכה - possible. Similarly, the משׁל mashal [fable or simile] or סמל [semel - symbol] is like a שׂמלה [simlah - garment]. On the one hand, it covers the inner content, but on the other hand it enables one to view and understand it.
If a person is lazy and does not exert himself in his studies, he will not see the inner meaning and will be left only with the outer ''covering'' - סכה. His Torah study will be full of unresolved questions and apparent contradictions. But one who labors indefatigably will discern - סכה - the truth hidden within the Torah. Labor [עמל - amal] leads to revelation of the inner secrets of both the person who studies and of the Torah which is studied. Thus, the letters following עמל in the alphabet are פנם [penim ''inner''].
פ follows ע
נ follows מ
ם follows ל
The Torah's outer cover, its revealed meaning, enables one to see its inner light. This may be compared to tinted glasses which are necessary in order to gaze at the sun.