Einstein on Physical Concepts

From The Evolution of Physics, Albert Einstein, Leopold Infeld, Simon & Schuster (1938) page 31

Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but has has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility of the meaning of such a comparison. But he certainly believes that, as his knowledge increases, his picture of reality will explain a wider and wider range of his sensuous impressions. He may even believe in the existence of the ideal limit of knowledge and that it is approached by the human mind. He may call this ideal limit the objective truth.

Einstein's sentiments here are close to that of Buddha, i.e.

All such notions as causation, succession, atoms, primary elements...are all figments of the imagination and manifestations of the mind.

From a letter to Eduard Study from Albert Einstein dated September 25, 1918

"The physical world is real." This is supposed to be the basic hypothesis. What does "hypothesis" mean here? For me, hypothesis is a statement whose truth is temporarily assumed, whose meaning however, must be beyond all doubt. The above statement seems to me intrinsically senseless though, like when someone says: "The physical world is a cock-a-doodle-doo." It appears to me that "real" is an empty, meaningless category (drawer) whose immense importance lies only in that I place certain things inside it and not certain others. It is true that this classification is not a random one but ..... now I see you grinning and expecting me to fall into pragmatism so that you can bury me alive. However, I prefer to do as Mark Twain, by suggesting that you end the horror story yourself, as you please.

<Real and unreal seem to me to be like right and left>

I admit that science deals with the "real" and am nonetheless not a "realist."

From Einstein and Buddha - Edited by Thomas J. McFarlane

Einstein - According to general relativity, the concept of space detached from any physical content does not exist.

Buddha - If there is only empty space, with no suns nor planets in it, then space loses its substantiality.

Einstein - Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. 

Buddha - Such notions as causation, succession, atoms, primary elements...are all figments of the imagination and manifestations of the mind. 

Einstein - Time and again the passion for understanding has led to the illusion that man is able to comprehend the objective world rationally by pure thought without any empirical foundations�in short, by metaphysics. 

Buddha - By becoming attached to names and forms, not realising that they have no more basis than the activities of the mind itself, error rises�and the way to emancipation is blocked. 

Einstein - In our thinking...we attribute to this concept of the bodily object a significance, which is to high degree independent of the sense impression which originally gives rise to it. This is what we mean when we attribute to the bodily object "a real existence." ...By means of such concepts and mental relations between them, we are able to orient ourselves in the labyrinth of sense impressions. These notions and relations...appear to us as stronger and more unalterable than the individual sense experience itself, the character of which as anything other than the result of an illusion or hallucination is never completely guaranteed. 

Buddha - I teach that the multitudinousness of objects have no reality in themselves but are only seen of the mind and, therefore, are of the nature of maya and a dream. ...It is true that in one sense they are seen and discriminated by the senses as individualized objects; but in another sense, because of the absence of any characteristic marks of self-nature, they are not seen but are only imagined. In one sense they are graspable, but in another sense, they are not graspable. 

Einstein - The belief in an external world independent of the perceiving subject is the basis of all natural science. Since, however, sense perception only gives information of this external world or of "physical reality" indirectly, we can only grasp the latter by speculative means. It follows from this that our notions of physical reality can never be final. We must always be ready to change these notions�that is to say, the axiomatic basis of physics�in order to do justice to perceived facts in the most perfect way logically. 

Buddha - While the Tathagata, in his teaching, constantly makes use of conceptions and ideas about them, disciples should keep in mind the unreality of all such conceptions and ideas. They should recall that the Tathagata, in making use of them in explaining the Dharma always uses them in the semblance of a raft that is of use only to cross a river. As the raft is of no further use after the river is crossed, it should be discarded. So these arbitrary conceptions of things and about things should be wholly given up as one attains enlightenment.