Polygon writer Brian Crecente tweeted this a few minutes ago:
"Bungie sent me a copy of The Second Jungle Book with a highlighted passage inside. pic.twitter.com/kkFhpNgaXl"
Tweet

The picture, he attached:

I cannot decipher the left part of the highlighted passage and I do not have a English copy of the Jungle Book, so... Sorry for no help here!

It's what's read in the trailer.

First two stanzas here:

Now this is the Law of the Jungle --
as old and as true as the sky;
And the Wolf that shall keep it may prosper,
but the Wolf that shall break it must die.

As the creeper that girdles the tree-trunk
the Law runneth forward and back --
For the strength of the Pack is the Wolf,
and the strength of the Wolf is the Pack.

Is that not a date for E3?

Well, E3 week, yes. (It's the day before E3 starts. It's also the date of the Sony Press Conference.)

10th June 2013?
(I wish)

The picture, he attached:

I cannot decipher the left part of the highlighted passage and I do not have a English copy of the Jungle Book, so... Sorry for no help here!