Let us now inquire what the effects are of odours generated in the outer world on animals. The odorous impressions produced may be pleasant or unpleasant, pleasant to one and unpleasant to another animal. What is it that constitutes this sensation of pleasure or displeasure? Professor Yaeger answers, It is harmony or disharmony which makes all the difference. The olfactory organs of each animal are impregnated by its own specific scent. Whenever the odorous waves of a substance harmonize in their vibration with the odorous waves emanating from the animal; in other words, whenever they fall in and agree with each other, an agreeable sensation is produced; whenever the reverse takes places, the sensation is disagreeable. In this way it is that the odour regulates the choice of the food on the part of the animal. In a similar way the sympathies and antipathies between the various animals are regulated. For every individual has not only its specific but also its individual scent. The selection between the sexes, or what, in the case of the human race, is called love, has its mainspring in the odorous harmony subsisting in the two individuals concerned. This individual scent--a variation of the specific odorous type--alters (within the limits of its speciality) with age, with the particular mode of occupation, with the sex, with certain physiological conditions and functions during life, with the state of health, and last, but not least, with the state of our mind. It is to be remembered that every time protoplasm undergoes disintegration, specific odours are set free. We have seen how sulphuric acid, or heat, when boiling or roasting meat, brings out the specific animal odour. But it is an established fact in science, that every physical or mental operation is accompanied by disintegration of tissue; consequently we are entitled to say that with every emotion odours are being disengaged. It can be shown that the quality of those odours differ with the nature of the emotion. The prescribed limits prevent further pursuit of the subject; I shall, therefore, content myself by drawing some conclusions from Professor Yaeger's theory in the light of the Esoteric Doctrine.