Complex sentence: A few years before, Watts had discussed the theme in his own book, "Nature, Man and Woman", in which he discusses the possibility of the practice being known to early Christians and of it being kept secretly by the Church.
Split into simpler sentences: A few years before, Alan Watts had discussed the theme in his own book "Nature, Man and Woman". There, he discusses the possibility of the practice being known to early Christians and of it being kept secretly by the Church.