Thirukkural-On Virtue-On Fate-Kural 372

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Destroying Fate can convert wisdom to folly; when on the other hand,
Fate decrees prosperity, even the dull become shrewd.

The idea is an amplification of the previous Kural. Prosperity and adversity in the present life are accounted for by Valluvar as due to the working out of Fate"s ordinances, which influence even the wise to commit acts of folly, while inducing the foolish to have flashes of intelligence.