Common sense is the most fairly distributed thing in the world, for each one thinks he is so well-endowed with it that even those who are hardest to … - René Descartes

Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.

Common sense is the best distributed commodity in the world, for every man is convinced that he is well supplied with it.

J'ai été nourri aux lettres dès mon enfance, et pour ce qu'on me persuadait que par leur moyen on pouvait acquérir une connaissance claire et assurée de tout ce qui est utile à la vie, j'avais un extrême désir de les apprendre. Mais sitôt que j'eus achevé tout ce cours d'études au bout duquel on a coutume d'être reçu au rang des doctes, je changeai entièrement d'opinion. Car je me trouvais embarassé de tant de doutes et d'erreurs qu'il me semblait n'avoir fait autre profit en tachant de m'instruire, sinon que j'avais découvert de plus en plus mon ignorance. (1ere partie, para 6)

Suppose [a person] had a basket full of apples and, being worried that some of the apples were rotten, wanted to take out the rotten ones to prevent the rot spreading. How would he proceed? Would he not begin by tipping the whole lot out of the basket? And would not the next step be to cast his eye over each apple in turn, and pick up and put back in the basket only those he saw to be sound, leaving the others? In just the same way, those who have never philosophized correctly have various opinions in their minds which they have begun to store up since childhood, and which they therefore have reason to believe may in many cases be false. They then attempt to separate the false beliefs from the others, so as to prevent their contaminating the rest and making the whole lot uncertain. Now the best way they can accomplish this is to reject all their beliefs together in one go, as if they were all uncertain and false. They can then go over each belief in turn and re-adopt only those which they recognize to be true and indubitable.

I resolv’d to faign, that all those things which ever entred into my Minde, were no more true, then the illusions of my dreams.