Crossing the Chasm is my favorite book on business. Its pages are packed with little gems, like this:
This is because they are buying a dream - which, to some degree, will always be a dream. The incarnation of this dream will require the melding of numerous technologies, many of which will be immature or even nonexistent at the beginning of the project. The odds of everything falling into place without a hitch are astronomical. Nonetheless, both the buyer and the seller can build successfully on key principles. [...]
The goal should be to package each of the phases such that each phase [...] provides the customer with a concrete return on investment that can be celebrated as a major step forward. Getting closure with visionaries is next to impossible. Expectations derived from dreams simply cannot be met. This is not to devalue the dream, for without it there would be no directing force to drive progress of any sort. What is important to celebrate continually the tangible and partial as both useful things in their own right, and as heralds of the new order to come.