Descartes - Rules For The Direction of The Mind
Philosophy from Descartes

RULE XVI

Matters, on the other hand, that do not demand our attention at the moment, though they are needed for drawing conclusions, are best represented by very brief symbols rather than by complete diagrams. For in this way our memory cannot be misled, and at the same time our thought will not be distracted by having to keep these things in mind while we are engaged in other deductions.