Meditation 8.12-13

12. When you are called from sleep with difficulty, revive the thought that to render social acts is according to your constitution and to human nature, but to sleep is what you share also with dumb animals. Now what to every creature is according to Nature is also more closely related to it, more part of its flesh and bone, yes, and also more agreeable.

13. Continually and, if possible, on the occasion of every imagination, test it by natural science, by psychology, by logic.