The fear of G-d involves relating to the A-lmighty as He is known by the Divine name Elokim, as the verse1 states: "Fear the A-lmighty (Elokim)," for the name Elokim denotes G-d's might and ability. In Shulchan Aruch Orach Chayim, Chapter 5, it is written that when the name Elokim is uttered, one should be aware of its meaning, namely, that G-d is powerful and can do whatever He pleases in both the physical world and the higher realms. A manifestation of His power is the fact that "Many are the A-lmighty's messengers."2 These messengers may take the form, Heaven forbid, of afflictions visited upon an individual. An example would be when good friends become bitter enemies, persecuting one another even in matters essential to life itself. Such actions may indeed be a result of G-d's will, as we find in the life of Dovid HaMelech. During the time that Dovid was suffering at the hands of his son Avsholom, he was cursed terribly by his one-time friend Shimi ben Geira. Dovid's response was that G-d had wanted him to be cursed,3 and that Shimi was just a messenger.
The same is true concerning good matters. Here too, "Many are the A-lmighty's messengers." When G-d is satisfied with an individual's conduct, even those that generally cause the person harm can become instruments which help nullify an evil decree pending against him.
When a person acts in an evil manner, however, G-d's response may demonstrate the attribute, Heaven forfend, of strict justice. Since this manner of conduct stems from the might of the Divine name Elokim, fear comes from Elokim as a matter of course.
Fear of G-d is therefore known4 as "the keys to the external chambers," inasmuch as it emanates from the external level of Malchus, for Malchus possesses both an internal and external level.
The difference between internal and external levels can be better understood by considering the three soul garments of thought, speech and action. Thought is internal while speech is external, and action is the most external of all. And within thought itself there are internal and external levels. Thoughts that deal with matters that are important to the individual are called "internal," whereas thoughts concerning inconsequential matters are "external." This is because the soul's illumination is more evident in matters of great personal import, and is much less evident in trivial matters.
The same is true regarding the higher realms. We say in the blessing of Yotzer:5 "All the praises of the actionsof Your hands." The term used is "actions," which implies an external level.
Concerning the praises offered by angels we say:6 "Who all stand in the heights of the universe and proclaim in awe, aloud and in unison, the words of the living G-d and Sovereign of the universe." Here the higher level of speech is alluded to. Though speech too is external, when compared to action it is internal. The point is that contemplation of the G-dly illumination which creates and vivifies the world and all its creatures involves the "external keys."
Herein lies the meaning of the verse:7 "And G-d (Elokim) made that He be feared." The name Elokim conceals G-d's Ineffable Name of Havayah, as indicated by the verse:8 "[Similar to] the sun and its sheath are Havayah and Elokim." Just as the sun itself is concealed what we observe is the sun shining through its sheath so too does the name Elokim conceal the Divine name of Havayah. That which is revealed is the name Elokim, from whence fear of G-d emanates, i.e., the "external keys."
In summary: G-d has many messengers for good or for its opposite, G-d forbid. Thought is generally internal, while speech and action are external. Within thought, there are internal and external levels. Thoughts which do not have a direct bearing upon a person are external; for this reason, meditation upon creation [which is removed from G-d's essence] involves the external keys. Fear of G-d comes from the Divine name Elokim.