Lyric discussion by WiredWizard 

This song is clearly telling people to stop being greedy. "Life is a waterfall, We're one in the river, And one again after the fall." This means that we are a soul before and after life "Swimming through the void We hear the word, We lose ourselves, But we find it all" Swimming through the void is going through life, the word we hear is 'lose'. We lose ourselves means we feel like we lost out in life, but we will find it all (heaven). "Cause we are the ones that want to play, Always want to go, But you never want to stay. And we are the ones that want to chose, Always want to play, But you never want to lose." We always take things and never want to give anything back in return. "Aerials, in the sky, When you lose small mind, You free your life." Aerials are either angels or souls. When you lose small mind (stop thinking only about yourself), you free your life (lead a life on the road towards heaven). "Life is a waterfall, We drink from the river, Then we turn around and put up our walls." We take what we can, but never give anything in return. "Aerials, so up high, When you free your eyes, Eternal prize." Aerials so up high would be in heaven. Your eyes eternal prize is also heaven.

There you go, it fits all the portions of the song perfectly. That is most likely the true meaning of the song, but it's my interpretation.

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