Every thought is wholly unique and thus the thought of a desire is never exactly alike in nature to that of its manifestation. Even so, your idea of what an actual manifestation will be like increases in accuracy as you approach the moment of its appearance. Furthermore, your thought defines the nature of the ultimate manifestation and thus the more desirable is the thought, the more desirable will be the resulting manifestation.
The further from the actual manifestation is a thought in time, the less accurate it is in its approximation due to the consistency of vibrations principle requiring the closest thought to be of the greatest likeness to the manifestation. Therefore, when a desire is first hatched, you may believe your idea of what it would be like were it to manifest to be accurate, but in actuality it is only an approximation. As you continue to think of that which is being manifested though, you will gain access to more information which will provide you with greater clarity that will in turn provide you with an extremely vivid understanding of what it would be like to experience the manifestation of your desire.
While you are seeing the future with your every thought, it becomes essential for you to understand that not only are you seeing the future being created, but you are actually the one who is creating it and thus all thoughts should be made to be as desirable as possible so that the future may be equally as desirable.