a) pick up a book which is the closest to you at the moment
b) open to page 123
c) find the third sentence
d) post it in your Live Journal (plus the instructions)
e) don't choose the book, just pick up the one closest to you.
Well, as usual, there are a few different options for this. The two books closest to me at the moment are Mythologies of the Ancient World, edited by Samuel Noah Kramer and The Three Musketeers (which I just finished today) by Alexander Dumas.
Mythologies has a poetry fragment at the top of the page, the third line of which is
"O Anunnaki, great gods,"
and the third actual sentence of text is
"Accordingly there were created two mortals having the names Ullegarra and Zallegarra (two Sumerian words whose meaning is still uncertain), and these were blessed by the gods with generous increase and rich abundance, so that they might celebrate the festivals of the gods 'day and night'."
The third complete sentence in my version of Musketeers is
"I know not whether I love you or not; but this I know, that I will never break my vow at the altar." (Queen Anne speaking to Buckingham)