ist in the air; his hair must be dishevelled, his eyebrows
low and narrow, his teeth clenched and the two corners of his mouth
set, his neck swelled and [his brow] wrinkled and bent forward as he
leans over his enemy.

92.

The desperate man must hold a knife and must have torn open his
garments, and with one hand he must be tearing open the wound; and you
must represent him with extended feet and the legs slightly bent and
his body leaning towards the earth, his hair flying and dishevelled.

[Sidenote: Notes on the Last Supper]

93.

One who was in the act of drinking leaves his glass in its place, and
turns his head towards the speaker. Another, twisting the fingers of
his hands together, turns with stern brows to his companions. Another,
with his hands spread out, shows their palms, and shrugs his shoulders
towards his ears; his mouth expresses amazement. Another speaks in the
ear of his neighbour, and he, as he listens to him, turns towards him,
lending him his ear, while he holds a knife in one hand and {138} a
piece of bread in the other, half cut through by the knife. Another,
in turning with a knife in his hand, has upset a glass on the table.
Another lays his hands on the table and looks fixedly. Another puffs
out his cheeks, his mouth full. Another leans forward to see the
speaker, shading his eyes with his hand. Another draws back behind him
who is leaning forward and sees the speaker between the wall and the
man who is leaning forward.

{141}

III

THOUGHTS ON SCIENCE

* *
*

[Sidenote: Necessity of Experience in Science]

There is no human experience that can be termed true science unless it
can be mathematically demonstrated. And if thou sayest that the
sciences which begin and end in the mind are true, this cannot be
conceded, but must be denied for many reasons, and firstly because in
such mental discourses experience is eliminated, and without experience
there can be no certainty.

[Sidenote: Theory and Practice]

2.

You must first propound the theory and then explain the practice.

3.

Let no man who is not a mathematician read the principles of my work.

4.

In the course of scientific exposition the demonstration of a general
rule derived from a previous conclusion is not to be censured.

{142}

[Sidenote: Certainty of Mathematics]

5.

He who blames the supreme certainty of mathematics feeds on confusion
and will never be able to