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By these veins we draw in much spirit (gas?), since they are the spiracles of our bodies inhaling air to themselves and distributing it to the rest of the body, and to the smaller veins, and they and afterwards exhale it. For the breath (pneuma) cannot be stationary, but it passes upward and downward, for if stopped and intercepted, the part where it is stopped becomes powerless. In proof of this, when, in sitting or lying, the small veins are compressed, so that the breath (pneuma) from the larger vein does not pass into them, the part is immediately seized with numbness; and it is so likewise with regard to the other veins.
