However, Böhm-Bawerk argues that if Marx's view of equilibrium is used, then one would have to say that the densities would cancel each other out and thus have "ceased to act", meaning they cannot explain why the balloon is now floating, which is incorrect as it is the relative densities that explain why the balloon floats. Thus for Böhm-Bawerk, it is simply inaccurate to state that supply and demand cannot explain equilibrium prices because they supposedly cancel each other out. Meghnad Desai, Baron Desai observed that there is also the prospect of surplus value arising from sources other than labour and a classic given example is winemaking. When grapes are harvested and crushed, labour is used. However, when yeast is added and the grape juice is left to ferment in order to get wine, the value of wine exceeds that of the grapes significantly, yet labour contributes nothing to the extra value. Marx had ignored capital inputs due to placing them all together in constant capital—translating the wear and tear of capital in production in terms of its labour value. Yet examples such as this demonstrated that value and surplus value could come from somewhere other than labour. Some Marxists argue that this criticism is erroneous because the labour theory of value was only ever meant to refer to freely reproducible commodities (i.e those not limited by scaricity), which would exempt goods such as wine, paintings, land and so forth. However, a counter-criticism is that this position makes no sense because non-freely reproducible commodities are still commodities and if Marx wishes to find a common factor that underlies all commodities, this common factor must exist in all commodities, rather than a narrow conception of commodities. Marx has also been criticised for not making clear in his writings when he is using "commodity" in this narrow conception. Since Marx argued that skilled labor was simply "condensed" labor, he has been accused of circular reasoning, as he resolves the issue of the value of skilled labor in the labor theory of value by assuming the labor theory of value is true so that skilled labor is judged by its exchange-value. It has been argued that Marx's effort to distinguish between skilled and unskilled labor was incoherent, as all labor ultimately required some degree of skill - true unskilled labor would only be possible with mindless automatons as workers still need to think in order to produce. This means it is not possible to reduce skilled labor to unskilled labor (and thus determine the number of unskilled labor hours) because all labor is skilled, meaning that value cannot be determined just by counting labor hours.