Looking for powerful abstractions [object oriented technology]

In this paper the author explores the ways that have helped him to become a better designer. Designers must be able to see the problem out there in the real world and solve it by applying the right tools and technologies. Like artists, object designers need to see in special ways to create good solutions - call this modeling or designing. Object technology is just one tool in a very rich toolbox and author discusses the fundamental design skill of finding objects. Finding the right level of abstraction takes practice and experimentation. There are times when both concrete classes and their common abstraction add value to a design, and there are times when they don't. To find good classes, experienced designers make distinctions based on significant behavior differences.