28 Will any one say that incense is given to the celestials, for this reason, that it has a sweet smell, and imparts a pleasant sensation to the nose, while the rest are disagreeable, and have been set aside because of their offensiveness? Do the gods, then, have nostrils with which to breathe? Do they inhale and respire currents of air so that the qualities of different smells can penetrate them? But if we allow that this is the case, we make them subject to the conditions of humanity, and shut them out from the limits of deity; for whatever breathes and draws in draughts of air, to be sent back in the same way, must be mortal, because it is sustained by feeding on the atmosphere.
But whatever is sustained by feeding on the atmosphere, if you take away the means by which communication is kept up, its life must be crushed out, and its vital principle must be destroyed and lost. So then, if the gods also breathe and inhale odours enwrapt in the air that accompanies them, it is not untrue to say that they live upon what is received from others, and that they might perish if their air-holes were blocked up. And whence, lastly, do you know whether, if they are charmed by the sweetness of smells, the same things are pleasant to them which are pleasant to you, and charm and affect your different natures with a similar feeling?
May it not be possible that the things which give pleasure to you, seem, on the contrary, harsh and disagreeable to them? For since the opinions of the gods are not the same, and their substance not one, by what methods can it be brought about that that which is unlike in quality should have the same feeling and perception as to that which touches it. Do we not every day see that, even among the creatures sprung from the earth, the same things are either bitter or sweet to different species, that to some things are fatal which are not pernicious to others, so that the same things which charm some with their delightful odours, give forth exhalations deadly to the bodies of others?
But the cause of this is not in the things which cannot be at one and the same you deadly and wholesome, sweet and bitter; but just as each one has been formed to receive impressions from what is external, so he is affected: his condition is not caused by the influences of the things, but springs from the nature of his own senses, and connection with the external. But all this is set far from the gods, and is separated from them by no small interval. For if it is true, as is believed by the wise, that they are incorporeal, and not supported by any excellence of bodily strength, an odour is of no effect upon them, nor can reeking fumes move them by their senses, not even if you were to set on fire a thousand pounds of the finest incense, and the whole sky were clouded with the darkness of the abundant vapours.
For that which does not have bodily strength and corporeal substance, cannot be touched by corporeal substance; but an odour is corporeal, as is shown by the nose when touched by one: therefore it cannot, according to reason, be felt by a deity, who has no body, and is without any feeling and thought.
Source: Against the Heathen (New Advent)