Depth and breadth, in this case, are not opposite directions on a straight line. They are vectors that only appear oppositional when viewed under specific time constraints. The more prolific a reader you are, the more efficiently you read, and thus your higher throughput dramatically compresses time.
If we're to speak about very specific increments of time and units of reading material -- say, you get to read N books over 1 week -- then sure, the zero-sum argument holds. But a lifetime is so much time, offering so much opportunity to the experienced reader, that time is almost effectively lifted as a constraint.
The only zero-sum quantities in this case are time and number of books. Depth and breadth of subject matter are better described as characterizing subcategories of #_books.
If we're to speak about very specific increments of time and units of reading material -- say, you get to read N books over 1 week -- then sure, the zero-sum argument holds. But a lifetime is so much time, offering so much opportunity to the experienced reader, that time is almost effectively lifted as a constraint.
The only zero-sum quantities in this case are time and number of books. Depth and breadth of subject matter are better described as characterizing subcategories of #_books.