"...But one of the central features of the Buddha’s strategy as a teacher was that even though his primary focus was on the mind, he nowhere stated any assumptions about what the mind is. As he said, if you define yourself, you limit yourself. So instead he focused his assumptions on what the mind can do.
To begin with, the mind can change quickly. Normally a master of the apt simile, even the Buddha had to admit that he could find no adequate analogy for how quickly the mind can change. We might say that it can change in the twinkling of an eye, but it’s actually faster than that.
And it’s capable of all sorts of things. Neither inherently good nor inherently bad, it can do a huge variety of good and bad actions. As the Buddha said, the mind is more variegated than the animal kingdom. Think of the many species of fish in the sea, birds in the sky, animals on the land and under the ground, whether extant or extinct: All of these species are products of minds, and the mind can take on a wider variety of forms than even that..."
- Thanissaro Bhikkhu