When the mind is braced by labor and invention, the page of whatever book we read becomes luminous with manifold allusion. Every sentence is doubly significant, and the sense of our author is as broad as the world. We then see, what is always true, that, as the seer’s hour of vision is short and rare among heavy days and months, so is its record, perchance, the least part of his volume. The discerning will read, in his Plato or Shakspeare, only that least part, - only the authentic utterances of the oracle; - all the rest he rejects, were it never so many times Plato’s and Shakspeare’s.

Still no definitive answer on this one then?

I have asked a couple of other people about this, and the consensus view is that it means:

"even though it may be / even if it were [many times Plato's and Shakespeare's]"

(which I think is more or less what I said last time).

Some typical examples of this usage of the archaic "were it never so" (randomly Googled) in which the meaning is perhaps slightly clearer:

... but I cannot let this day pass without sending you some word or other, were it never so insignificant. (= "...even though it might be insignificant")

If the first of these fail, the Power of Adam, were it never so great, never so certain, will signifie nothing to the present Governments and Societies. (= "... even though it may be very great, very certain ...)

There are two competing theories about what "many times Plato's and Shakespeare's" means. The first is that "many times" just refers to the volume of material that the authors wrote (and hence the volume that is being rejected). The second is that it means "[even if it were] many times superior to Plato's and Shakespeare's [work]".
Thanks a lot, Mr Wordy.....

I really need to give this subject some great time.......