The Jewish philosophers often spoke about חומר and צורה [as did the ancient gentile philosophers...]. Simplistically, the חומר is raw material and the צורה is what gives the חומר it's meaning and purpose. For example: The body is the חומר and the soul is the צורה. The wood is the חומר and when it is fashioned into a table, that gives the חומר a צורה.
There is a machlokes between Beis Shammai and Beis Hillel. Beis Shammai holds that first the heavens were created and then the earth. Beis Hillel holds that first the earth was created and then the heavens. The Rogochover explains that Beis Shammai holds that the צורה [the heavens which gives the world its spiritual meaning] is the עיקר of creation and the חומר is secondary. Beis Hillel maintains that the actualization of Hashem's will is in the חומר and that is primary. Thus, the חומר was created first.
This is sooooo Rogochover-ee. He, in his great geonus, took a seemingly concrete, straightforward argument about a historical, cosmological event and showed how it was really a deep philosophical argument. What is the primary goal of creation - the חומר or the צורה? [He continues to explain that really, Torah-wise, the צורה is the עיקר as Beis Shammai holds. Strange that he seems to reject שיטת בית הלל. He writes וזה באמת בכל התורה - דעיקר צורת הדבר]
He added a gemara in Shabbos which seems to have NOTHING to do with our topic.... but it really does.
The gemara [Shabbos 62b] says that a woman may not go out wearing a spice bundle and with a flask of balsam oil and if she goes out she is liable to a chatas - so said R' Meir. R' Eliezer exempts her. In what case were these words stated [that she is exempt]? When they have spice or oil in them. But if they don't have anything in them and are empty - she is liable.
Rav Adda Bar Ahava said that this teaches that one who takes out less than a shiur of food in a kli is liable for taking out the utensil even though he is not liable for taking out the food. For taking out a spice bundle that has no spices [or oil] is comparable to taking out less than a shiur of food in a kli and the braisa says that the wearer is liable. Thus, one who takes out less than a shiur of food should be liable. Rashi explains that a little bit of the aroma clings to the kli which is considered less than a shiur because all there is left in the kli is the scent with no concrete חומר at all. Since a person is liable for taking out the kli he should also be liable for taking out a kli with less than a shiur of food. In neither case do we say that the kli is subordinate to what is inside because there is less than a shiur.
Rav Ashi argues and says that generally when one takes out less than a shiur of food in a kli he is exempt because the kli is subordinate to the food. In the case of the bundle of spices in the kli one is liable because the scent that remains is considered completely inconsequential and all that is left is the kli. But if something of substance remains, even though it is less than a shiur one would be exempt because the kli is subordinate to what is inside.
Smell is considered צורה. The gemara says that the neshama enjoys the pleasure of smell. So the argument is whether smell alone, צורה, with no חומר, is considered significant and thus comparable to less than a shiur of food [Rav Adda bar Ahava] or if it is completely disregarded because we only consider the חומר to be significant [Rav Ashi].
The Mishna [Uktzin 3/6] records an argument between Beis Shammai and Beis Hillel whether Ketzach is considered food and susceptible to tumah or not. Beis Shammai says that it is not susceptible to tumah while Beis Hillel says that it is.
What is Ketzach? Ketzach is a type of Arabian seed [or fennel] which has a harmful odor but is healthy to eat [Brachos 40a]. Beis Shammai says that it is not susceptible to tumah because the צורה, the smell, is harmful and since that צורה is the עיקר it is not considered food and is thus tahor. Beis Hillel follows the חומר which is the beneficial eating aspect of ketzach and thus considered it food and thus susceptible to tumah. The same argument applies as to whether it is chayav in trumos and maasros. Beis Shammai doesn't consider it food [and it is exempt] while Beis Hillel does.
לזכות נעכא גיטל בת רחל אסתר לזרעא חיא וקיימא די לא יפסוק מפתגמי אורייתא