The absurdity involved in the notion of greater or smaller values is, in short, the assumption that an individual may be _at the same moment_ under different conditions. The _homo oeconomicus_ is not at the same moment in _a_, _b_, _c_, _d_, _e_, _f_ ... but when he is in _b_, he is no longer in _a_; when he is in _c_ he is no longer in _b_. He has before him only one action, approved by him; this action rules out all the others which are infinite, and which for him are only _actions not preferred_ (non-values). Certainly physical objects form part of the data of economics; and these, just because they are _physical_, are _measurable_. But economics does not consider physical things and objects, but _actions_. The physical object is merely the brute matter of an economic act: in measuring it we remain in the physical world, we do not pass over to that of economics, or else, when measured, the economic fact has become volatile. You say that 'political economy only concerns itself with choices, which fall on things that are variable in quantity and capable of measurement'; but pardon me, dear friend, you would be much perplexed if you had to justify this wholly arbitrary limitation; and if you had to show that the attribute measurabilility influences in any way the attribute of belonging to economics. I think that I have explained, shortly, but adequately for a wise man like yourself, the reasons why the mechanical conception of the economic principle is untenable. If calculations and measurements come into problems that are called economic they do so just in so far as these are not problems in _pure_ economics. This non-mechanical datum, which is an economic datum, you call _choice_. And this is all right. But _to choose_ means to _choose consciously_. A choice made unconsciously, is either not a choice or not unconscious. You speak of the _unconscious actions_ of man; but these cannot be the _actions_ of the man _in so far as he is man_ but movements of man _in so far as he is also animal_. They are _instinctive_ movements; and instinct is not choice _except metaphorically_. Hence the examples you bring forward of dogs, of cats, of sparrows, of rats, and of asses from _Buridano_, are not facts of _choice_; and hence are not economic facts. You consider animal economics as an unfruitful science, which exhausts itself in descriptions. Look more closely and you will see that this science does not exist. An economics of the animals, understood in the sense of the naturalists, has not been written, not because it is not worth while, but because _it is impossible to write it_. Whence could it be obtained unless from books such as the _Roman de Renart_ and the _Animali parlanti_? This analysis ought to lead us to conceive of an economic datum as an act of man; _i.e._ as a _fact of human activity_.