De omnibus dubitandum

I have concluded the evident existence of God, and that my existence depends entirely on God in all the moments of my life, that I do not think that the human spirit may know anything with greater evidence and certitude.

Just as we believe by faith that the greatest happiness of the next life consists simply in the contemplation of this divine majesty, likewise we experience that we derive the greatest joy of which we are capable in this life from the same contemplation, even though it is much less perfect.

How can you be certain that your whole life is not a dream?

When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream. How can you be certain that your whole life is not a dream?

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

It must not be thought that it is ever possible to reach the interior earth by any perseverance in mining: both because the exterior earth is too thick, in comparison with human strength; and especially because of the intermediate waters, which would gush forth with greater impetus, the deeper the place in which their veins were first opened; and which would drown all miners.