The heightening of dream experiences may, however, be very complete in, as it were, every direction: thus a botanical friend joined a large party for a pleasant country excursion, in the course of which, while sitting in a waggonette, an acquaintance, a miller, standing in the road, handed up to him a dog-rose. In the course of a dream of agreeable emotional tone on the night following, this incident was reproduced, but the miller had become an angel, who handed down to him, instead of up from below, a flower which was a moss-rose. Thus, not only do the actual stimuli taking place during sleep suggest to dream-consciousness imagery of a magnitude out of all proportion to their real intensity, but even the repercussion of the day's incidents in dreams under the influence of a favourable emotional tone may partake of the same heightening influence. We may say, therefore, that while the excessiveness of dream imagery is mainly due to the conditions of the nervous sensory and motor channels, there is also probably a heightened affectability of the cerebral centres themselves--perhaps due to their state of dissociation or absence of apperception[85]--which leads us in our dreams to react extravagantly to the stimuli that reach the brain. A lady tells me that she often dreams of being very angry at things which, on awaking, she finds are mere trifles that would never make her angry when awake.[86] It is a common experience that the things which, in our dreams, impress us as beautiful, eloquent, witty, profound, or amusing, no longer seem so, or only seem so in a much slighter degree, when we are able to recall them awake. All these various considerations lead us up to a central fact in the psychology of dreaming: the controlling power of emotion on dream ideas. From our present point of view we are now able to say that the chief function of dreams is to supply adequate theories to account for the magnified emotional impulses which are borne in on sleeping consciousness. This is the key to imagination in dreams. From the first we have seen that in dream life the mind is always freely and actively reasoning; we now see what is usually the real motive and aim of that reasoning. Sleeping consciousness is assailed by waves of emotion from various parts of the organism, but is entirely unable to detect their origin, and, therefore, invents an explanation of them. So that in sleep we have to weave theories concerning the unknowable origin of our emotions, just as when we are awake we weave theories concerning the ultimate origin of the totality of our experiences. The fundamental source of our dream life may thus be said to be emotion.[87]