It is a pity that, by the fault of a narrow education, he should have so completely immolated himself to that one idea of his, especially as the slightest modicum of common-sense would teach him its utter impracticability.
—Nathaniel Hawthorne, The Blithedale Romance, 1852
Modicum derives via Middle English from Latin modus, meaning "measure." A modicum is literally a small measure of something, and implies an amount that meets a bare minimum.
Source: Merriam-Webster Online: It's the Little Things: 8 Handy Words When You Just Need a Pinch of Something