His early writing on spirituality, though still in print and still popular, I find less helpful than his later writing about his interfaith journey.
One of his later books (published in 1965) was his own interpretation of the ancient Doaist philosopher Zhuangzi (Chuang Tzu). It's not a translation (though multi-lingual, Merton did not speak or read Chinese) but rather a comparison of translations, read through the lens of Merton's own spiritual quest.
I was reading it again recently and was taken by Merton's interpretation of Zhuangzi's sixth chapter, "The True Man," though being now inclusive most recent translations of Zhuangzi speak of the "genuine person," or "true humanity." Here is part of Merton's poem of Chapter Six of Zhuangzi, with modification for inclusive language:
What is meant by a "genuine person"?
The genuine person of old was not afraid
When they stood alone in their views.
No great exploits.
No plans.
If they failed, no sorrow.
No self-congratulation in success.
They scaled cliffs, never dizzy,
Plunged in water, never wet,
Walked through fire and were not burnt.
Thus their knowledge reached all the way
To Tao.
The genuine person of old
Slept without dreams,
Woke without worries.
Their food was plain.
They breathed deep.
A genuine person breathes from their heels.
Others breathe with their gullets,
Half-strangled.
...
The genuine person of old
Knew no lust for life,
No dread of death.
...
Easy come, easy go.
They did not forget where from,
Nor ask where to,
Nor drive grimly forward
Fighting their way through life.
They took life as it came, gladly;
Took death as it came, without care;
And went away, yonder,
Yonder!
They had no mind to fight Tao.
They did not try, by their own contriving,
To help Tao along.
These are the ones we call a genuine person.
Minds free, thoughts gone
Brows clear, faces serene.
Were they cool? Only cool as autumn.
Were they hot? No hotter than spring.
All that came out of them
Came quiet, like the four seasons.
Thomas Merton, was then, on a quest. His seeking took him to the East, metaphorically in his growing love of eastern spirituality and philosophy, and literally as it was on a visit to Bangkok, in 1968, that he was tragically killed in an accident— five years younger than I am now.
Perhaps he had learned from Zhuangzi that the quest is in the end is not an outward quest from some "thing," or some "method," some religion or ideology, but rather a quest to become at home in your own person, in your own humanity. In other words, to find yourself in the happy state of Zhuangzi's "genuine person."
I let the reader ponder the sage's wisdom, to find for themselves what they will.
For me, Zhuangzi speaks of a state of inner balance, being comfortable in embodiedness, at home in the humanness of it all, at home with the spark of the divine within. It speaks of being untouched by the outward circumstances of life, neither fretting over the past or worrying about the future. It speaks of happy contentment, neither too emotionally hot or cold.
It speaks to me too, as a taiji player, of a breath that arises "from the heals"—the deep energetic connection with nature, with earth and heaven.
Did Thomas Merton reach the end of his quest? It's impossible to say, as he did not tell us. I hope so. Yet, his death in the middle of a literal journey might suggest he was still on the inner quest, still looking for the "genuine person."
+Ab. Andy
Section of the Zhunagzi from: Merton, Thomas (2010-03-30). The Way of Chuang Tzu (Second Edition) (Kindle Locations 816-852). New Directions. Kindle Edition.