For the happiest life, days should be rigorously planned, nights left open to chance.
— Mignon McLaughlin

Learning and sex until rigor mortis.
Maggie Kuhn rigors quote

Thus, in a sense, mathematics has been most advanced by those who distinguished themselves by intuition rather than by rigorous proofs.
— Felix Klein

The circumstances of human society are too complicated to be submitted to the rigor of mathematical calculation.
— Marquis De Custine

If this work seems so threatening, this is because it isn't simply eccentric or strange, but competent, rigorously argued, and carrying conviction.
— rigors quotation by Jacques Derrida