The Tome of Great Knowledge can't really be called a Tome at all. Featuring an illusory cover bound around illusory pages the book functions like a mundane tome but has no physical weight to it, or to its pages, and there is little to no tactile presence to the thing at all. It's kind of like light hardened to have the appearance of a book, or a book made so massless as to have the properties of a beam of light.
Strait away upon peering at the cover one notices that its hard light construction is both beautifully intricate and mechanically identical to any other locked tome requiring a verbal command to open and access it. There is a latch lock but such a thing is for thieves to break their lockpicks in. Opening the cover requires the same command as to lock it again, "Librum Apertum de Scientia".
The first thing one notices is that it is a book with pages that have the appearance of fine silk, weightless, tactile-less, hard to flip through without gloves or wet fingers silk. Overall even the pages have a solid sheen to them and it is pristine in its presentation. The tome is not without a few other shall we say, special quirks. Its contents tend to shift or flicker and flow as they sometimes move across individual pages and while opening the whole thing goes from a shimering brass-copper sheen to a silver glow that emanates from the pages of the book. Otherwise, it is beautifully illuminated with full-color pages throughout.
It is said the tome was found just laying on the altar of the mountaintop shrine in the aftermath of the dragons attacking of Druidhold in the final days of the Godswar, most likely freed from where it was stored previously for so long even the Elder Gods likely do not know when it was first lost. The Tome is now kept locked in the Vault of Parimon by orders of the First Council as many consider the work to be an apocryphal work.
The contents of the Tome of Knowledge is a collection of the oral stories and traditions told by the first men ages ago. Although the insights into their existence are deep and meaningful, possibly earth-shattering in its revelations, there is a good reason why it is considered questionably factual or false, there appear no spell, incantation or even recipe within the pages of the book. Strangely the final quarter of the book seems to contain procedures of complete nonsensical words and terminology, though if this is due to an error in translation of the written material or the ravings of a lunatic remains to be proven.