The usual starting place for dependent origination is with ignorance, but way back at the beginning of the sutta quoted above, when Sariputta defined ignorance in the structure usually applied to the four noble truths (what is ignorance, what is its origin, its cessation, the path to its cessation?) he said that the arising of the taints brought the arising of ignorance, and the cessation of the taints ended ignorance, so we could say that dependent arising goes one more step back from ignorance — except that we can see from the above, that ignorance is one of the taints. How’s that work?
First, if we look at the other two — sensual desire (kama) and being (bhava) — we might find that these have their source in ignorance, too: both can represent our natural tendency to follow one path or another around beliefs in the self: the belief that sensual desires will make us happy, or the belief that the becoming of the self will lead to ultimate bliss — both of these beliefs are founded on the ignorance we’ve just explored in depth through those twelve links — so what we seem to have here is ignorance, ignorance, and more ignorance.
On a more practical level — one we can see for ourselves if we just look around — it’s quite true that ignorance breeds ignorance when it comes to dukkha and what’s being described in dependent arising. Modern science, when it tells us about confirmation bias, tells us that we will protect our most cherished ideas from any threat by doing just what has been described by the Buddha here — by liking what is like us and our ideas, by rejecting what is not like us and our ideas — this is exactly our ignorance feeding more ignorance because it keeps us from seeing that others may know things we don’t know, and our conclusions may be based on less information than we need or could have to make them.
In the final analysis, ignorance is the root of the problem, and knowledge is the cure, but it is a very specific ignorance, and very specific knowledge. As long as we are unaware of the way we come into the world with a need for a sense-of-self, a need that — in its excesses — gets us into trouble, we can’t find a way out of the problem. The first links in the chain of causation describe the situation we are born into, a way of being that goes back as far as we can see — to the birth of “the First Man”, or really, to our origins as described by our myths. What’s pointed out is the way we are driven by this need for the self to exist, a need that drives us to seek confirmation of who we are and what part we play in the individuality of everything around us, information we seek through our senses. This drive gets detailed in a sequence — loosely modeled on Vedic rituals — that describes the rituals we (in our ignorance) perform of seeking confirmation of the self through our senses, interpreting it in ways that support our sense of who we are and the way the world works, and developing our interpretation into increasingly dogmatic views, until we bring to birth a sense of self that is visible to the world through our actions. But, because we are mistaken in so many of our assumptions (and we are blinded by our ignorance of the way things are working — at a very deep level — into being sure we are right in those assumptions) all our efforts lead not to the bliss we’d like, but to a tangle of problems so deeply interwoven into our lives that — without specific help seeing what’s going on — most of us won’t be able to find a way out.
Dependent arising describes the problem, and in so doing, gives us the knowledge we need to effect a cure. It all comes down to ending those “taints” — the natural confusion about what’s going on that has us wanting this or wanting that, thinking it will satisfy our cravings. As long as we don’t recognize the deepest basis for our cravings, we can never break free. As soon as we realize that our sense that “This is good, I like this, it suits me, it fits with my worldview, it satisfies” is all about comforting ourselves about our selves, we are on the road to recovery.