You can mark in desire the rising of the tide, as the appetite more and more invades the personality, appealing, as it does, not merely to the sensory side of the self, but to its ideal components as well.

But unfortunately Locke treated ideas of reflection as if they were another class of objects of contemplation beside ideas of sensation.

The mental act of sensation which issues in reflex movement is so simple as to defy analysis.

Hence, in desiring, the more the enjoyment is delayed, the more fancy begins to weave about the object images of future fruition, and to clothe the desired object with properties calculated to inflame the impulse.

It may be added, to prevent misunderstanding, that when I speak of contemplated objects in this last phrase as objects of contemplation, the act of contemplation itself is of course an enjoyment.

... when demand is being destroyed by expensive oil just as expensive oil is incentivising increased production - it should come as no surprise that at some point the markets would react.

The perceptive act is a reaction of the mind upon the object of which it is the perception.