Rabbi Yishmael read the commandment against idolatry with a scope that went far beyond golden calves and carved statues. When the Torah says "You shall not make unto Me gods of silver and gods of gold" in (Exodus 20:20), Rabbi Yishmael understood it as a prohibition against depicting any heavenly being at all.
The phrase "unto Me" is the key. God is saying: do not make images of the beings who serve before Me on high. This means not just idols in the conventional sense, but any artistic representation of the celestial realm. Do not make the likeness of angels. Do not make the likeness of the ofanim — the mysterious heavenly creatures described in the visions of Ezekiel, the wheel-like beings covered in eyes. And do not make the likeness of the cherubim — the winged figures that guard sacred spaces throughout Scripture.
This interpretation dramatically expands the scope of the prohibition. It is not enough to refrain from worshiping foreign gods. One must also refrain from creating images of God's own attendants. The heavenly court is off-limits for artistic representation, no matter how pious the intention behind the artwork might be.
The reasoning reflects a deep concern about the human tendency to turn any image into an object of veneration. Even if someone created a likeness of an angel purely as decoration, the risk of that image eventually becoming an object of worship was too great. The rabbis understood that the line between art and idolatry is thin, and the safest approach was to prohibit depictions of the divine realm entirely.
Rabbi Yishmael's reading sets an extraordinarily high standard for monotheistic purity — one that shaped Jewish attitudes toward religious art for millennia.