Encouraging Words has proven to be one of my favorite reads in Zen Buddhism. The book is aptly titled, for this book is indeed encouraging. While the content is for persons already acquainted with Zen Buddhism, not beginners, Aitken had a way of speaking simply the profound Dharma. The work is intimate, for addressed to his students and Aitken speaks as one with them, not an authority over them. I was much impressed with Aitken's attitude as seen through his words: a wise teacher and more so for being humble of heart and mind.
Aitken models for us an ordinary enlightenment, meaning he does not present himself as somehow special at all - rather, a human among humans, and does not encourage us feverously tp pursue enlightenment experiences. Rather, his message is simply: Nirvana is here. We're already in the Pure Land. Being true to the Dharma, Aitken does not encourage mystification but intimacy with the everyday.
So, if you have at least a beginning grasp of Zen Buddhism, I recommend this work to you. If not, I recommend you begin elsewhere.