There is no doubt that John Owen had a firm grasp on this topic, which is critical to believers. Yet I quit reading the book in the middle of the 9th chapter. It was written in the 1600's. The vocabulary, the long protracted sentences, the old English, and the multiplied appositives make the reading of the book drudgery. To be useful, this book needs to be rewritten. If you like outdated English, you will probably do well with it.
This book is not light reading, but it is life-changing. I am working through parts of it for the fourth time. His beginning approach of what mortification of sin 'is not' was a little confusing until I read the rest of the book. When I understood how John Owen explained what it is - then I could start to let go of the misconceptions that he was innumerating.