Verse 86

दृषदो विद्यते शक्तिः कदाचिच्चलनैधसाम् ।न पुनर्मनसामस्ति शक्तिः स्पन्दावबोधने

In plain words

Stones, at times, possess the power to strike fire from fuel by their friction; but minds, in turn, have no power at all to perceive spanda.