When in the sciences or techniques one states that a certain problem is unsolvable, a rigorous demonstration of such unsolvability is required. And when a scientist submits an article to publication, the least that its referees demand is that it be intelligible. Why? Because rational beings long for understanding and because only clear statements are susceptible to be put to examination to verify whether they are true or false. In the Humanities it is the same, or it should be, but it is not always so. Nietzsche reproached John Stuart Mill's clarity. Henri Bergson, although an intuitionist himself, wrote clearly and declared that "clarity is the philosopher's courtesy."