In the beginning one reverses nonvirtue.
In the middle one reverses the view of a self.
In the end one reverses all views.
Those who know this way are wise.
This verse describes the three stages of Middle Way analysis, which are a very important component of especially the Kagyü presentation of the Middle Way. It would be difficult not to develop major misunderstandings of the view without a good understanding of these three stages. (That sentence sounded pretty professorial and pedantic, but, hey, it's hard to write a blog about this stuff!)
The first stage, which corresponds to "In the beginning one reverses nonvirtue," is called the stage of no analysis. At this stage, no analysis into whether things are real or not is conducted. The existence of things is taken at face value, and the student emphasizes rejecting nonvirtuous or harmful actions and adopting positive actions. I find a verse by Vasubhandu to harmonize with this meaning nicely:
Abiding in discipline and engaging in hearing and contemplating
Excellently prepares one for meditaton.
The second stage, which corresponds with "In the middle one reverses the view of a self," is called the stage of slight analysis. Here one begins to apply (actually, in contrast to the somewhat misleading name, quite a freaking bit of) analysis into whether things exist or not. Breaking down conceptions that falsely set up a status of existence, one concludes that one's perceptions of the existence or realness of things were false. To familiarize oneself with this conclusion, one emphasizes the thought of nonexistence. (Thus we find in the Heart Sūtra, "There is no eye, no ear, no nose, no tongue, no body, no mind...")
The third stage, which corresponds with "In the end one reverses all views," is the stage of thorough analysis. "Thorough," according to Dzogchen Ponlop Rinpoche, primarily means "beyond" here, for it is at this stage where one lets go of and transcends even the thought of nonexistence to nakedly experience the nature of things without any conceptual label.
So, in sum, you could say that the first stage provides one with a stable environment that prepares one to work with one's more subtle thoughts and assumptions about the way things are. The second stage robustly challenges our preconceptions about the solidness of the things to which we cling in our lives. And the third stage, following the "break down" stage, allows us to let go of even the concept of dismantling, to finally experience reality without any reifying concepts.
May we all genuinely traverse the path of these three stages! E Ma Ho!