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  • Gustavo Lopez thinks this is interesting:

Because the class you’re reusing is confused about what it does and contains several tangled up responsibilities, it has many reasons to change. It may change for a reason that is unrelated to your use of it, and each time it changes there’s a possibility of breaking every class that depends on it.

From

Cover of Practical Object-Oriented Design in Ruby: An Agile Primer

Note

Increase chance of changing (& breaking) the class ... if it does too much.