this is always a tension in writing mathematics textbooks. at one end of the extreme you have e.g. Bourbaki which are very dry, but prove a great deal very efficiently and in the utmost generality. on the other hand you have textbooks which may be not as comprehensive and will intersperse the text with illuminating examples which historically would have been the original motivation for the subject. which is best really depends on your point of view and level of sophistication in the subject. usually I try to have both types of book at hand.<p>what would be great is if typesetting tools improved sufficiently so that one could choose &#x27;beginner&#x27; or &#x27;advanced&#x27; mode when reading a maths textbook. perhaps that is too fanciful!