The first sefirah of every level is its Keter which is the desire to bring it about, for if there were no desire for it, it couldn’t exist. This principle applies both above, in regard to the creation of the world, and below, in man. It is an observable fact, that if one does not desire something, he will not do it. This is true even when he does something he does not want to do. In such a case, there is another, overriding desire which compels him to do that which he would not otherwise do. For instance, if a person hates his job, he does it anyway because his desire to survive overrides his hatred for the work. Above too, the desire for something is what gives it its existence. Therefore, the Keter of Atzilut is the desire to bring about the world of Atzilut.
Now, there are really two parts to the sefirah of Keter. The external aspect of Keter is desire, and its inner aspect is pleasure. In truth, these two aspects are inseparable from each other, for the one cannot be found without the other. Furthermore, pleasure does not necessarily precede desire nor must desire precede pleasure. In any case, of the two, pleasure is the internal and desire is the external, simply because a desire is for the pleasure. Therefore, even though desire may precede pleasure, nevertheless, it is only for the pleasure. We may therefore conclude that there is a desire and a pleasure for everything that exists and that pleasure is the internal of the two. It is the desire and pleasure for something that brings it into being and keeps it in existence. This principle applies in the negative sense as well. There is even a pleasure and desire which gives evil its existence. How can this be understood? What pleasure or desire could G-d possibly have in evil?
As we see, most games, sports, stories, novels and movies involve an opponent in order to create a challenge. Even computer games have “bad guys”. The reason for their existence is to destroy them. It is the adversity of the opponent that creates the challenge and gives excitement and purpose to the game. If there were no opposition to overcome, there would be no pleasure or sense of accomplishment in the game whatsoever. Likewise, though it is not a game, the existence of evil in the world is for the pleasure gained by its destruction and to create free choice and challenges for human beings.
These two parts of Keter are called Atik Yomin (The Ancient of Days), and Arich Anpin (The Long Face). Atik Yomin corresponds to pleasure and Arich Anpin corresponds to desire.
The difference between the desire of Arich Anpin (The long Face) and the desire of Adam Kadmon (Primal Man) is that the desire of Adam Kadmon is not yet for any specific thing. Rather, it is the general perception of himself, as a whole, which includes many particular desires in it. In Adam Kadmon the specific desires are completely concealed in a way of a heyulie. Arich Anpin, on the other hand, is already a desire for something “outside of himself”, so to speak. It is a desire for the revelation of a specific thing. Furthermore, in Adam Kadmon, the desire is actually not for anything external altogether. It is all still solely for himself. An example of this is a person who desires a beautiful car. In his A’K (Adam Kadmon) it is not actually a car that he wants. Rather, the desire of his A”K (Adam Kadmon), is that he envisions himself in the car. It is all about himself, not the car. Only in Arich Anpin does the desire for the car itself become revealed. We, therefore, see that the desire of Arich Anpin is already for something outside of Himself, whereas in Adam Kadmon it is still all about Himself. This is the way it is in the desire, which is Arich Anpin. However, the pleasure of it, is still all about Himself. For this reason, Atik Yomin, which is the pleasure of it, still relates to the Self, and is still considered to be part and parcel of the Self. In contrast, Arich Anpin already relates outward, toward the world. For this reason it is considered to be the source of Atzilut (the world of Emanation).