One of the most important things you need to do as a designer is read about your craft. Read about the philosophy, practice, and history of design. Consuming books on topics related to design and art provides you with fresh new perspectives on approaching and evaluating design problems, while teaching you about the design process as a whole and it's many variations. More importantly, reading about it improves your design vocabulary.
Language shapes thought, humans think and imagine based on things that they have already seen. Even wild and far out thoughts are extrapolations from some base of your reality, or some analogy you have mentally constructed with your words. In that way your language and vocabulary become a framework for your thought process. Language "is a powerful tool in shaping thought about abstract domains," and thus shapes the way you deal with design problems.
It is as the old adage says, when all you have is a hammer, everything begins to look like a nail. By increasing your vocabulary and the number of ways you have to describe design concepts and perspectives, you are increasing your mental tool box.
That is why designers are, and should be collectors. Designers are cultural scavengers that collect experiences and the objects that represent them. Paul Rand said "the artist is a collector of things imaginary or real. He accumulates things with the same enthusiasm that a little boy stuffs his pockets. The scrap heap and the museum are embraced with equal curiosity." The same should be said for collecting words and ways of describing. Your vocabulary along with your experiences form a framework for conceptualization. Reading about varied perspectives on design, especially about ways of describing design related concepts, can help you produce better creative output, with the added bonus of being able to better communicate design to people of different backgrounds than your own.
Remember that words and descriptions are a map of reality, but the map is not the territory. Words are simply symbols we use to represent ideas of varying abstractness, so the more we have, the better off we are as designers.