Avodah Zarah, Chapter 3, Mishnah 5. The basic question this Mishnah comes to answer is: what is the law regarding a mountain that non-Jews attribute independent power to and worship - a phenomenon that is not rare at all. Is the mountain forbidden to derive benefit from? May one quarry its stones? May one plant a vineyard on it? The answer is that it is permitted, since the mountain is the handiwork of the Holy One, blessed be He, and human beings do not have the ability to turn it into an object of worship that would become forbidden to derive benefit from.
In contrast, something whose making involves human participation - such as a tree that a person planted - does become forbidden to derive benefit from, even though it is attached to the ground, because a person had a share in creating it. This is the distinguishing feature that underlies the Mishnah.
But the Mishnah is more complex than that: the verse that speaks about the mountains and the hills mentions trees in the very same breath, and seemingly they are all on the same level. If so, the question arises: why is a mountain that was worshipped not forbidden to derive benefit from, while a tree that was worshipped - an asheirah - is forbidden? This is the question we will now address.
The words of the Mishnah:
"HaGoyim ha'ovdim es heharim v'es hagevaos - hen mutarin u'mah she'aleihem asurin" - non-Jews who worship the mountains and the hills: the mountains and hills themselves are permitted, but what is upon them is forbidden. The mention of "the non-Jews" is not meant to exclude a Jew who worshipped them, since that makes no difference in the law; rather, this is the language of the verse: "You shall utterly destroy all the places where the nations worshipped... their gods, upon the high mountains and upon the hills." The mountains and hills themselves remain permitted - one may quarry from them and plant on them; but whatever was placed upon them, such as an ornament with which they decorated the mountain, becomes forbidden.
And the source for this is, "shene'emar: 'Lo sachmod kesef v'zahav aleihem v'lakachta'" - as it says: "You shall not covet the silver and gold upon them and take it." The word "upon them" teaches that even in a case where the object of worship itself is not forbidden for some reason, the silver and gold upon it are forbidden. In our case the object of worship is the mountain, which is not forbidden, while the items placed upon it and adorning it are forbidden.
The derivation of Rabbi Yosi HaGlili:
Why does one who worships a mountain not make it into an object of idolatry forbidden to derive benefit from? On this Rabbi Yosi HaGlili derives from the wording of the verse: "Eloheihem al heharim" - their gods are upon the mountains, "v'lo heharim eloheihem" - and not the mountains as their gods; the mountains remain mountains, and they are not to be regarded as their gods in this context. And likewise "eloheihem al hagevaos" - their gods are upon the hills, "v'lo hagevaos eloheihem" - and not the hills as their gods; the hills themselves have no status of "their gods" such that they would be forbidden to derive benefit from.
And why is an asheirah forbidden?
The question has still not been resolved, for that very same verse also mentions "a leafy tree," yet an asheirah is forbidden to derive benefit from. To this the Mishnah answers: "mipnei sheyesh bah tefisas yedei adam" - because it has in it the grasp of a human hand. The tree did not grow on its own but was planted by a person, and once human beings have a share in it, they have the power to render it forbidden. A mountain is different, since it exists independently of man, and likewise the sun and the moon and similar things, which exist without any human involvement and therefore remain permitted.
The Mishnah continues and establishes a general rule: "v'chol sheyesh bo tefisas yedei adam - asur" - and anything that has in it the grasp of a human hand is forbidden. Things that came into being through human involvement, such as the planting of a tree, even though they are attached to the ground and attached to the mountain, are caught in the prohibition of benefit on account of their being worshipped, since they were made by human hands at least in part.
The words of Rabbi Akiva:
The difficulty still remains: why does the verse mention trees and mountains together, as though their status were identical? Rabbi Akiva - who was younger than Rabbi Yosi HaGelili and belonged to the generation after him - comes to resolve this point through a fresh reading of the plain meaning of the verse. "Amar Rabbi Akiva: ani avin v'adun lefanecha" - let me come and explain to you the logic behind the verse.
According to him, the verse is not dealing at all with the status of these things and the question of what becomes forbidden and what does not. Rather, it is giving practical guidance: when you come into the Land of Israel you have a mitzvah to destroy every place of idolatry, and where will you find them? On the mountaintops, on the hills, and under every leafy tree. And this is the language of the Mishnah: "Kol makom she'atah motzei har gavo'ah v'givah nisa'ah v'etz ra'anan - da sheyesh sham avodah zarah" - wherever you find a high mountain, a lofty hill, or a leafy tree, know that there is idolatry there. These are the places one must search out in order to fulfill the command to destroy idol worship from the Land.
In summary: in this Mishnah we learned that mountains and hills that were worshipped remain permitted for benefit, while what is upon them becomes forbidden, as derived from "You shall not covet the silver and gold upon them." Rabbi Yosi HaGelili expounded, "their gods are upon the mountains - and not the mountains themselves are their gods," and the principle that emerges is that "whatever has in it the grasp of human hands is forbidden" - and for this reason an asheirah planted by a person is forbidden, while a mountain, created by Heaven, is permitted. Rabbi Akiva added that the mention of the mountains, the hills, and the leafy tree in a single verse is not a statement of halachic status, but a sign of where the places of idolatry are to be found so that they may be destroyed.