It is the custom of the Samurai to always keep a sword close at hand, and be ready for battle, even to the extend of having a wooden sword or a sword without blade with him when he bathes. Likewise, it should be the custom of the artist to always have a pen or brush close at hand and be ready to paint.
Jacobo Pontormo was a Florentine master who painted anxious figures. He anticipated expressionism but was out of his time and other painters considered him a weirdo. The last 10 years of his life he worked on a single painting and refused to show it to anyone.
His withdrawn personality was similar to Michelangelo but very different from Leonardo. Amongst the great masters Leonardo da Vinci was the most sociable.