"Kokoro" in Japanese is the Heart/Mind. The "kanji" (Chinese/Japanese character) in this image may be translated as either "heart" or "mind" depending on the context in which it is used. In Zen there is no context -- only the one heartmind. Splitting the one from the other is trouble. This truth is revealed in one of the most important teachings of Buddhism, The Heart Sutra. And then there is this poem from Li Po:

The birds have all vanished into deep
skies. The last cloud drifts away, aimless.

Inexhaustible, Ching-t’ing Mountain and I
gaze at each other, it alone remaining.