Rich -:
1. How can such polar opinions exist on one science?
Cessation is not an action but, well, cessation of action. From the point of view of cessation, you can't act your way to cessation. This paradox is acknowledged even in the Pali suttas (there's a simile of going to the park somewhere - the park is not the result of you going there), and also in MCTB, in such phrases as "fruition is always a complete surprise".
The ego-trap is where the ego inflates itself on how it's going to act itself to cessation, all by itself. In my experience, practice will become very humbling when carried through. But some personalities may have a hard time with this humbling/humiliating process of getting one's nose rubbed in how limited one's own powers of surrender are.
Rich -:
2. How are these two viewpoints unified? (which surely they must be at some point)
It's not a matter of resolving the paradox within its constraints, because that's not really possible. Within the paradox, there are only positions to take on this or that side. Some positions may be more suitable for some people. The assumption that practice really makes a difference is a powerful one for many people, including myself.
Cessation in the case of the paradox happens when the paradox loses its capacity to ensnare, entangle,
fetter the mind.
Until that happens, there are useful analogies and rules of thumb to go by:
"The finger pointing at the moon"
"Awakening happens by accident, but practice makes you more accident-prone"
"Fake it till you make it"
"Surrender is practice, letting go is the fruit"
"Eigtfold path (practice) has to be
developed, cessation (fruit) is
realized" (from the discourse on setting the Dharma Wheel in motion)
"Gateless Gate"
"Grace vs. Works" (the everlasting Christian doctrinal discussion)
Cheers,
Florian
P.S. basically, what Tommy said so much more succinctly.