In ep1s1 cold open (literally the beginning) Liandrin said: "When you touch the source, you make it filthy. That power is for the woman, the woman alone"
For the watchers there is clearly just one source, till now
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Reading a lot of post here about BS works make me feel like a black sheep. My second preferred book for the entire series after Shadow Rising is Gathering Storm. I barely survived after Crossroads of twlilight. The first BS Book got me enterely hooked again.
I disliked (hated) the Epilogue and some Mat's chapter but, a part from that, it was great.