An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

Variant: When it is not in our power to follow what is true, we ought to follow what is most probable.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

It is possible that I am dreaming right now and that all of my perceptions are false.

By 'God', I understand, a substance which is infinite, independent, supremely intelligent, supremely powerful, and which created both myself and everything else [...] that exists. All these attributes are such that, the more carefully I concentrate on them, the less possible it seems that they could have originated from me alone. So, from what has been said it must be concluded that God necessarily exists.

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

But possibly I am something more than I suppose myself to be.