Dear Paul,
It is not by doubting the words of the Guru that one gains knowledge, but by
trying to understand them, and by practicing the teaching. If you have doubts
over the validity of a statement, then humbly question the teacher. Dismissing
the whole teaching is not helpful.
The rose and its thorns is just a metaphor to convey the idea of duality,
positive and negative, but even here we can see that the actual role of the
thorns is to protect our beautiful rose, which means the thorns are also
precious. Do you get the idea?
.