These three cannot be fully grasped.
Therefore they become one.
These are the first five lines of chapter 14 of the Tao Te Ching, in the translation by Stephen Addiss and Stanley Lombardo, and I read them as describing the Seeker, who has not yet found the Way. Jesus quoted Isaiah on people having ears but not hearing. We call it dim, faint or subtle because we do not grasp the Way.
Ursula LeGuin, working with a literal translation of the pictograms and many different English translations, gives me a quite different impression.
Look at it: nothing to see.
Call it colourless.
Listen to it: nothing to hear.
Call it soundless.
Reach for it: nothing to hold.
Call it intangible.
it merges into oneness.
This concerns the follower of the Way. S/he moves in the Way, because it is natural to her/him. We do not touch it, it is just what is, how we are. The unthinkable thought which one cannot plan, but does. (Or something- there is Seeker in me yet.)
James Legge, a wordy 19th century translator, wrote, With these three qualities, it cannot be made the subject of description, and hence we blend them together and obtain The One. We have found the way, which we create by blending the Equable, the Inaudible and the Subtle.
Here is another translation:
Looked at but cannot be seen – it is beneath form;
Listened to but cannot be heard – it is beneath sound;
Held but cannot be touched – it is beneath feeling;
These depthless things evade definition,
And blend into a single mystery.
The Tao is what is, blending whether anyone sees it, or not.
Look at it, it cannot be seen
It is called colorless
Listen to it, it cannot be heard
It is called noiseless
Reach for it, it cannot be held
It is called formless
These three cannot be completely unraveled
So they are combined into one
So, the translation affects how I understand the text, or do not understand it. The translation can only equal the understanding of the translator.