Shantideva, in A Guide to the Bodhisattva's Way of Life, reminds us in the final "Wisdom" section that "for as long as the necessary conditions are assembled, for that long even illusions will occur."
It seems simple enough, right? Whatever experience we're presently having arises from specific conditions that immediately preceded that experience. And those conditions arise, accordingly, from those that preceded those. And so forth and so on.
For Westerners, two issues occur here that are worth examining. First, once we get the point that the present arises from specific causes and conditions, it occurs to us that we might have a little more say in fashioning our present life by generating those conditions that we find most supportive of the goals we wish to achieve: happiness, compassion, altruism, the mind of enlightenment. Fine. We are responsible for our happiness.
But second, Shantideva implies that our conventional mind is fundamentally a set of causes and conditions that generate themselves perpetually over many lifetimes. That's troublesome to most of us because we've grown up thinking of our minds as solid entities that are occasionally afflicted with unhappiness or depression and blessed at times with happiness and joy. But there is a core, we assume, that entertains these emotions, and this core has something to do with our personality.
To give up this core, then, or to see it as an assemlage of causes and conditions, is to give up our personality. And that's hard for a Westerner to do.
But it gets easier if we understand that harboring these notions of personality are cultivating in turn the very delusions that give rise to our suffering. What we learn from Shantideva is that we can, in fact, change things at such a profound level that our very conception of mind will be transformed. Shantideva teaches us a very simple but profound truth: We must use the mind to transform the mind.
And that is the mind's major purpose—to transform itself.