One has to be cautious in reading 'Zen' books ... because 'Zen' really comes in two somewhat different flavors. I have spoken about this before.
On the one hand is the flavor of those Zen schools that teach that we are out to achieve something, usually called 'Satori' or 'Enlightenment', and this is done though Practice, primarily Zazen (and typically Zazen focused on 'solving Koans'). This perspective, to paint with a broad brush, is usually associated more with the 'Rinzai' school (or lineages that are 'Rinzai-Soto hybrids, like Maezumi Roshi's lineage and the Sanbokyodan) than traditional Soto school teachings.This 'Satori' clears away illusions and lets us realize our 'True Self before our mother and father were born'.
On the other hand, the traditional Soto teaching (as represented by Dogen, for example) is that what we need to 'achieve' is the realization of radical non-achievement. We both see through life (seeing that all phenomena are impermanent, unsatisfactory and lack 'self-hood') AND that all phenomena and life in general are 'just what they are' with not a darn thing to change. This realization is illusions cleared away, our 'True Self', now and before our mother and father were born. The 'Koans' melt away and are resolved, WIsdom and Compassion manifest. We drop all judgments and categorizations about life, likes and dislikes, and just allow things to be even beyond ideas of "being" or "not being" (although, of course, we simultaneously require judgments, 'being/not being' and other ideas, catergorizations and likes-dislikes in order to live daily life, so we keep these on another 'channel' at the same time). The way we realize this is not by thinking that 'Practice" (such as Zazen) is to achieve 'enlightenment', but that Practice and all of life --is-- already enlightenment itself.
The key to our approach is that giving up all idea of a revolution --IS-- a revolution achieved, for this is attaining non-attaining!
The difference between the two approaches may be like, in the first case, running all over looking for your nose, and in the second case, finding your nose by going no place and realizing it was there all along and you did not need to do anything to 'find' it! I like to think that both approaches get you to the same place in the end (which is no place, and just your nose being where it belongs), but 'Zen' books can be misleading as they are phrased differently depending on the perspective, but don't often say that they are of one type or the other. One of the most radical examples of the first 'goal oriented' types is 'Three Pillars of Zen' (a book I do not recommend because of its radical insistence on an explosive, life changing 'Kensho' experience) and books by D.T,Suzuki, and of the second type, 'Opening the Hand of Thought' (which we are reading in the Book Club) and 'Zen Mind Beginners Mind' by Shunryu Suzuki (don't confuse your Suzukis!!).
So around here I teach 'Just Sitting' Shikantaza, which means that we practice very very hard for no goal at all, in order to realize that there is nothing about life to add or take away, it all is what it is ... like a mountain is just a mountain, and the 'Venus d'Milo' is perfectly the 'Venus d'Milo' despite her missing limbs.