“mystery that has no meaning

Magritte addressed the question of its meaning in 1959 in a letter to an art historian
twenty years after the painting had been done:

“The question you ask concerning the conception of the painting La Durée poignardée
(Time Transfixed doesn't seem to be a very accurate translation)
can be given an exact answer insofar as what I was thinking of.
As for trying to explain why I thought of painting the image of a locomotive
and why I was convinced this painting should be executed,
I cannot know nor do I wish to know.....

the problem presented itself as follows:
how to paint this image so that it would invoke mystery?
-that is the mystery to which we are forbidden to give meaning,
lest we utter naive or scientific absurdities;
mystery that has no meaning.....

I thought of joining the locomotive image with the image of a dining room fireplace
in a moment of ‘presence of mind.’
By that I mean the moment of lucidity that no method can bring forth.
Only the power of thought manifests itself at this time....

Archimedes' ‘Eureka!’ is an example of the mind's unpredictable presence.”