The greatest weight-
What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your live will have to return to you, all in the same succession and sequence--even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again, and you with it, speck of dust!' Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: 'You are a god and never have I heard anything more divine.' If this thought gained possession of you, it would change, you as you are or perhaps crush you.
~Friedrich Nietzsche, The Gay Science 341
trans. Walter Kaufmann
This is not my favorite translation, and I have a very long commentary about this passage and its relation to the eternal recurrence, but it's perhaps the best place to start. The "greatest weight" is the thought of the eternal recurrence, and it seems to suggest something along the lines of determinism combined with a circular notion of time. (I think both are slightly mistaken. The important part--in a much-too-small nutshell--is the affirmation of the whole cosmos, despite all the things we might like to change.)
[Speaking of things we might like to change, this post's readability was labelled "elementary school." I concur with B'Yo!'s assessment: I don't understand their heuristic.]
What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your live will have to return to you, all in the same succession and sequence--even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again, and you with it, speck of dust!' Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: 'You are a god and never have I heard anything more divine.' If this thought gained possession of you, it would change, you as you are or perhaps crush you.
~Friedrich Nietzsche, The Gay Science 341
trans. Walter Kaufmann
This is not my favorite translation, and I have a very long commentary about this passage and its relation to the eternal recurrence, but it's perhaps the best place to start. The "greatest weight" is the thought of the eternal recurrence, and it seems to suggest something along the lines of determinism combined with a circular notion of time. (I think both are slightly mistaken. The important part--in a much-too-small nutshell--is the affirmation of the whole cosmos, despite all the things we might like to change.)
[Speaking of things we might like to change, this post's readability was labelled "elementary school." I concur with B'Yo!'s assessment: I don't understand their heuristic.]