We usually distinguish between two kinds of meat: beast meat and fish meat, and in both there are signs of impurity. The Torah gave us signs by which to know how to avoid them so as to not fall into the domain of impurity in them.
In fish, it gives us the signs of fins and scales. When one sees these signs in fish, one knows how to be cautious and not fall into the hands of impurity. Snapir (fin) implies Soneh-Peh-Ohr (hating-mouth-Light). This refers to Malchut, called “mouth,” and all the Lights come from her, which is discerned as faith.
And when one sees that he is in the state of a taste of dust, at a time when one should believe, then one knows for certain that one should correct one’s actions. And this is called “ Shechina (Divinity) in the dust.” One should pray to raise Divinity from the dust.
Kaskeset (scales) means that at a time of Snapir one is unable to work at all. Rather, when one overcomes the Snapir, a question concerning Providence appears in one’s thought. And this is called Kash (straw). In that state one falls from one’s work. Later, one prevails and begins to work above reason, and another doubt concerning Providence appears in one’s mind.
It follows that one has two times Kash, which are Kas-Keset (scales). And every time one prevails above reason, he ascends and then he descends. Then one sees that he cannot prevail, due to the proliferation of the doubts. In that state, one has no other choice but to cry to the Creator, as it is written, “and the Children of Israel sighed by reason of the bondage, and their cry came up unto God, and He delivered them out of Egypt,” meaning from all the troubles.
Our sages said a famous rule, that the Creator says, “He and I cannot dwell in the same abode,” that is, because they are opposite from one another. This is so because there are two bodies in man—the inner body and the outer body. The spiritual sustenance dresses in the inner body, discerned as faith and bestowal, called “mind and heart.” And the outer body has the corporeal sustenance, which is knowing and receiving.
And in the middle, between the inner body and the outer body, there is a middle body, which does not bear its own name. However, if one performs good deeds, the middle body clings to the inner body, and if one performs bad deeds, the middle body clings to the outer body. Thus, either one has corporeal sustenance or spiritual sustenance.
It follows that since there is oppositeness between the internal and the external, if the middle body clings to the inner body, it is considered the death of the outer body. And if it clings to the outer body, it is death to the inner body. This is so because in that state, the choice is in the middle body: to continue adhering to Kedusha (Sanctity), or to the contrary.