Our task is to look at the world and see it whole.

We see what our ancestors have always seen: a great Chain of Being which seems to divide naturally into four sections--four "kingdoms," as they used to be called: mineral, plant, animal, and human...

No one has any difficulty recognizing the astonishing and mysterious difference between a living plant and one that has died and has thus fallen to the lowest Level of Being, inanimate matter.  What is this power that has been lost?  We call it "life."    ... There is nothing in the laws, concepts, and formulae of physics and chemistry to explain or even to describe such powers.  x [this power] is something quite new and additional, and the more deeply we contemplate it, the clearer it becomes that we are faced here with what might be called an ontological discontinuity or, more simply, a jump in the Level of Being.

From plant to animal there is a similar jump, a similar addition of powers, which enable the typical, fully developed animal to do things that are totally outside the range of possibilites of the typical, fully developed plant.  These powers, again, are mysterious and, strictly speaking, nameless..However, since we cannot talk without words, I shall attach to these mysterious powers the label consciousness...

Moving from the animal to the human level...Man has powers of life like the plant, powers of consciousness like the animal, and evidently something more...This power (z) has undoubtedly a great deal to do with the fact that man is not only able to think but is also able to be aware of his thinking...and to direct consciousness.

Matter (m), life (x), consciousness (y), self-awareness (z)--these four elements are ontologically--that is, in their fundamental nature--different, incomparable, incommensurable, and discontinuous.  Only one of them is directly accessible to objectife, scientific observation by means of our five senses.  The other three are none the less known to us because we ourselves, every one of us, can verify their existence from our own inner experience.

We never find life except as living matter; we never find consciousness except as conscious living matter; and we never find self-awareness except as self-aware, conscious, living matter.

--E. F. Schumacher--A Guide for the Perplexed

These traditional terms (mineral, plant, animal,  human)  seem to be Pirsig's evolutionary levels from the point of view of biology.

Schumacher describes the difference between them as being indescribable, then goes on with a description of the qualities of the differences.

He's as good as Pirsig, and is definitely talking about the same thing.

What Jaynes defines as "conscious" corresponds to Schumacher's "self-aware", both congruent to Pirsig's "intellectual".

The full text is definitely worth reading.  You can order it here: E.F.Schumacher A Guide for the Perplexed