Barthes'
Mythologies rather charmingly exposes bourgeois society and the myths that frame it. Using a structural or semiotic approach, Barthes is able to dissect and analyze a variety of things (essentially any aspect of popular culture) and find how they function within a mythological framework (and how they effect society or how society uses them).
Barthes' rhetorical approach is centered on oppositions (especially in language), which we see particularly in Soap-powders and Detergents. Barthes shows us how different types of soaps are sold by way of what they signify, for example:
"Chlorinated fluids, for instance, have always been experienced as a sort of liquid fire, the action of which must be carefully estimated, otherwise the object itself would be affected, 'burnt'. The implicit legend of this type of product rests on the idea of a violent, abrasive modification of matter: the connotations are of chemical or mutilating type: the product 'kills' the dirt. Powders, on the contrary, are separating agents: their ideal role is to liberate the object from its circumstantial imperfection: dirt is 'forced out' and no longer killed..." (My own italics)
Soaps, here, have been polarized to their extremes, one as a violent modifying agent, the other as liberating. The relationship of signifier and signified here is important; the chlorinated fluid is the signifier, the violent destruction of dirt is signified (what the soap means). Likewise, the powder is the signifier, and the nonviolent exiling or expulsion of the dirt is signified.
Barthes was certainly being purposefully humorous in his deep analysis of soaps, but then again, he can be no humorous than the fact that such an analysis is possible (and works!) We as consumers are sold things, not necessarily for what they are, but because of their implicit meaning, the invisible mythologies that are literally packaged with (and as) the product itself. Delicate material requires delicate powder to free it from the enmeshed dirt, the tougher grime must be violently removed by a tougher soap. The irony of the oppositions is that in the end, they are of the same source, "A euphoria, incidentally, which must not make us forget that there is one plane on which Persil and Omo are one and the same: the plane of the Anglo-Dutch trust Unilever." Barthes saves his best move for last, and the punch line delivers very effectively. Of course, one must come to expect effective rhetorical gestures from a critic mostly concerned with structures, signs, and rhetoric.
Wine and Milk, similarly, is centered on an opposition:
Bachelard was probably right in seeing water as the opposite of wine: mythically, this is true; sociologically, today at least, less so; economic and historical circumstances have given this part to mil. The latter is now the true anti-wine; and not only because of M. Mendes-France's popularizing efforts (which had a purposefully mythological look as when he used to drink milk during his speeches in the Chamber, as Popeye eats spinach), but also because in the basic mophology of substances milk is the opposite of fire by all the denseness of its molecules, by the creamy, and therefore soothing, nature of its spreading."
Wine and milk are opposites, like different soaps, both rhetorically and mythologically. But Barthes isn't really concerned with milk, rather, he focuses on wine. Wine is no longer signified, but becomes signifier for something else, namely Frenchness, something healthy and high-minded (as opposed to an alcohol like whiskey). But just as in his soap essay, Barthes finishes the wine piece with the sharpest piece of commentary, "And the characteristic of our current alienation is precisely that wine cannot be an unalloyedly blissful substance, except if we wrongfully forget that it is also the product of an expropriation." By the end of the two essays, we know (or should know) that the mythologies surrounding these aspects of domestic culture are exactly innocent, but rather serve as active agents for the bourgeoisie in forming and enforcing values or some other end, making the humor in the essays rather dark in its implications.