The author appears to be overlooking the usefulness of comparisons to relevant averages or historical highs and lows - clearly such comparisons can be useful wh

The author appears to be overlooking the usefulness of comparisons to relevant averages or historical highs and lows - clearly such comparisons can be useful when plotting meteorological data, for example. Furthermore, it does not follow that, in those cases, all data should be in the form of differences or ratios with respect to the relevant datum. From these considerations, the author's principle could be generalized to 'lines should be meaningful.'