On Youth And Old Age, On Life And Death, On Breathing   

control over life and death, for it results synchronously that when

respiring animals are unable to breathe they perish. Again, it is

absurd that the passage of the hot air out through the mouth and

back again should be quite perceptible, while we were not able to

detect the thoracic influx and the return outwards once more of the

heated breath. It is also nonsense that respiration should consist

in the entrance of heat, for the evidence is to the contrary effect;

what is breathed out is hot, and what is breathed in is cold. When

it is hot we pant in breathing, for, because what enters does not

adequately perform its cooling function, we have as a consequence to

draw the breath frequently.



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It is certain, however, that we must not entertain the notion that

it is for purposes of nutrition that respiration is designed, and

believe that the internal fire is fed by the breath; respiration, as

it were, adding fuel to the fire, while the feeding of the flame

results in the outward passage of the breath. To combat this

doctrine I shall repeat what I said in opposition to the previous

theories. This, or something analogous to it, should occur in the

other animals also (on this theory), for all possess vital heat.

Further, how are we to describe this fictitious process of the

generation of heat from the breath? Observation shows rather that it

is a product of the food. A consequence also of this theory is that

the nutriment would enter and the refuse be discharged by the same

channel, but this does not appear to occur in the other instances.



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Empedocles also gives an account of respiration without, however,

making clear what its purpose is, or whether or not it is universal in