Is mentation the product of ignorance?
The answer is: no.
It is in most cases the product of Maya, which is the power of the Self through which, although alone, it appears to be multiple, thus making ignorance possible, but not necessary. In some cases, it is the product of Grace, which is the power of the Self through which it puts an end to ignorance, but not to Maya. For the sage and for the ignorant alike, there is Maya, seeming multiplicity. The difference is that the sage, unlike the ignorant, is not fooled by it.
In fact Grace and Maya are inseparable. They are like the two sets of lanes of a single freeway, one moving away from home, the other leading back to it. The same universe can be contemplated as a multiplicity of objects in its immanence or as Consciousness in its transcendence, just like a water color landscape can be seen as a collection of trees, stones, houses, birds, etc or as a single piece of paper.