Leviticus 17:7

Neither shall they offer any more their sacrifices unto idols which are like unto demons, after which they have wandered. This shall be an everlasting statute to them, unto their generations.

to the satyrs [Hebrew: las̀s̀e⊂irim] These are the demons, so called because when one sees them, one’s body convulses [Hebrew: yis̀ta‘er]. Also, the lunatics who see these demons experience visions of goat-like creatures [Hebrew: s̀e’irim]. The word no longer teaches that, in Egypt, this had been Israel’s practice.

they stray [literally: they prostitute themselves] Anyone who summons demons, or believes in them, is faithless to his God. He thinks that benefit or harm can come from a source other than God, the Glorious and Awesome. This passage does not mention the resident alien, because it pertains to Israel’s sacrificial offerings; however, the subsequent passage does mention the resident alien. Here the resident alien is mentioned because Israel must not allow an alien to offer idolatrous sacrifices within the Land of Israel. Likewise, they may not drink blood, which is forbidden because it represents life: the life of the body depends on the blood (A man lives by means of the blood which comes from his heart.)

AND THEY SHALL NO MORE SACRIFICE THEIR SACRIFICES ‘LA’SE’IRIM’ AFTER WHOM THEY GO ASTRAY. “La’se’irim means ‘unto the demons.’ Similarly it states, ‘u’se’irim’ (and demons) shall dance there.” This is Rashi’s language, derived from the Torath Kohanim. 9:8. Now Rabbi Abraham ibn Ezra wrote that “the demons are so called [se’irim, a word which is connected with sei’ar, meaning ‘hair’], because on seeing them a person’s hair stands up on his body. But it is likely that they are called se’irim [a word which also means ‘goats’], because mentally deranged persons see them in the form of goats. And the word ‘more’ [in the verse before us, and they shall no ‘more’ sacrifice …] indicates that the Israelites used to do so in Egypt. After whom they go astray denotes that whoever seeks after them and believes in them ‘goes astray’ from his G-d, since he thinks that there is a power that can cause good or evil apart from the Glorious and Fearful Name.” [Thus far the words of Ibn Ezra.]
Now Rabbi Abraham ibn Ezra has indeed hinted at the truth concerning the word “more,” as I have written above. The name se’irim will also be made clear to you there. They are also called sheidim [“demons,” as Rashi interpreted here — a word which is connected with shodad, meaning “devastate, despoil, ruin”], because they dwell in “devastated” places, such as the desert, and their principal habitat is in the far corners [of the earth], such as the northern extremity of the earth which is wasteland on account of the cold climate.
Know that just as the formation at the original Creation of man’s body as well as that of all living creatures, vegetation and minerals, was from the four elements, which were combined by Divine power to form material bodies which as a result of their thickness and coarseness could be perceived by the five senses, even so there was a creation from only two elements, fire and air, resulting in a body which cannot be felt, nor perceived by any of the [five] senses, just as the soul of an animal cannot be perceived by human senses because of its delicacy. The body [of these creatures of two elements] is of a spiritual nature; on account of its delicacy and lightness it can fly through fire and air. And just as the combination of the four elements in any object is the cause of its existence and its destruction [since everything that is composite must ultimately revert to its …

חקת עולם תהיה זאת, not to offer sacrifices to the demons even though they were not being equated with deities in any manner, but were considered only as creatures that could be employed by their human masters. They even used to employ such demons for errands to distant countries. We have documented proof of this in the case of Joseph Shida [the demon named Joseph].(Sanhedrin 59, compare Nachmanides) and about the demon who was prominent in the household of Rav bar Rav Ashi (Chulin 105). Had such demons been considered deities it is inconceivable that people of Rav Ashi’s stature or Rav Pappa’s stature would have had any track with them whatsoever.
It is reported in the Talmud that whereas little is known about the manner of these demons’ creation, they are known to eat and drink just as human beings. It is further worthy of mention that the sages, collectively, referred to the phenomenon of the demons as מזיקים, destructive, harmful phenomena. They multiply in a manner similar to humans and they die a regular death. They see without being seen themselves.
Apparently, although they are composed of composite material, their bones are extremely thin and transparent. The author speculates that just as ordinary human beings in common with the animals possess a נפש חיוני “intangible life-force” which, seeing that it dies with the body it inhabits, as distinct from the human נשמה which is an intangible spirit emanating in the celestial regions, is basically terrestrial in nature, these demons are “powered” by such a life-force. The reason we find that “life-force” referred to on occasion as נפש is the fact that it cannot exist without its tangible partner, the one which feeds on food and drink secured from what is available in our terrestrial universe.
Consider the very fact that the Torah describes “blood as the life-force” (Deuteronomy 12,23). If someone were to sacrifice blood to such a creature, especially, seeing that it is powerful enough to sustain the life of such creatures, the blood sacrificed to such creatures would be equivalent to keeping these demons alive. (compare Maimonides, Moreh Nevuchim,3,46 on the subject).
This would be a violation of the statement in Chulin 105 כל מידי דצייר וחתים וכייל ומני לית לן רשותא למשקל מינעה. This is a conversation between the “owner” of a demon, Mar bar Rav Ashi, according to which the demon who had not paid back a loan on time to the “owner” claimed that his power to collect objects in this world …