Something similar is to be observed in calligraphy in its own right, i.e., without accompanying paintings, as in the scrolls below.
The text reads, first in the scroll on the right, "Do no evil." The scroll on the left reads "Perform every good." The quotation is a well-known aphorism. The calligrapher, the famous Rinzai priest Ikkyû, brings the couplet into a visual performance by beginning at the top of each line with a (relatively) straightforward shin style rendering. As the line is written down the scroll, though, the script style changes to gyô and finally sô style. Changes in script style exhibited like this, in a single line of calligraphy, perform for us, each time we see them, the writing itself, by making visually apparent the movement of the writer. In the kanji at the bottom of each scroll you see areas of white left untouched as the brush, now partly emptied of its ink, speeds through the requisite stroke. These areas within the stroke are called "flying white." To produce them on mulberry paper or silk like this requires speed and resolution in creating the stroke in question. It manifests a preconscious bodily understanding of how the kanji is to be written, and in peformance itself, offers not time for reflection, much less hesitation. The spontaneity captured here is something much prized in Japanese art. Here it is made an explicit element of the calligraphy, but it is no less important, if far less obtrusive, in a painting like the one you see below:
Again, the image you have been considering is only a part of the whole picture surface. Like the image of the kôan about catching a catfish with a gourd we say earlier, this image is meant to be read together with a set of inscriptions. Here's a shot of the full painting: