Now, since our condition ...

Now, since our condition accommodates things to itself, and transforms them according to itself, we no longer know things in their reality; for nothing comes to us that is not altered and falsified by our Senses. When the compass, the square, and the rule are untrue, all the calculations drawn from them, all the buildings erected by their measure, are of necessity also defective and out of plumb. The uncertainty of our senses renders uncertain everything that they produce.
Now, since our condition accommodates things to itself, and transforms them according to itself, we no longer know things in their reality; for nothing comes to us that is not altered and falsified by our Senses. When the compass, the square, and the rule are untrue, all the calculations drawn from them, all the buildings erected by their measure, are of necessity also defective and out of plumb. The uncertainty of our senses renders uncertain everything that they produce.

Quotes from the same author

I care not so much what I am to others as what I am to myself. I will be rich by myself, and not by borrowing.
If there is such a thing as a good marriage, it is because it resembles friendship rather than love.
The most certain sign of wisdom is cheerfulness.
The most unhappy and frail creatures are men and yet they are the proudest.
It is much more easy to accuse the one sex than to excuse the other.