Human beings are spatially and temporally limited parts of the whole that we call "universe"; yet we experience ourselves and our feelings as separate from the rest, a kind of optical delusion of our consciousness. 

footnotes of n_Einstein_Translation.php included in entryNote.php, e_Einstein_HumanDelusion.php, and e_personalMeta.php.

Ein Mensch ist ein räumlich und zeitlich beschränktes Stück des Ganzen, was wir „Universum“ nennen. Er erlebt sich und sein Fühlen als abgetrennt gegenüber dem Rest, eine optische Täuschung seines Bewusstseins. Das Streben nach Befreiung von dieser Täuschung ist der einzige Gegenstand wirklicher Religion. Nicht das Nähren der Illusion sondern nur ihre Überwindung gibt uns das erreichbare Maß inneren Friedens.    Albert Einstein, 1950.

Einstein wrote the above (bold emphasis added), in ink, in a note now held in the Albert Einstein Archives, Jerusalem. The edit I have made  is of the translation, written in another hand, that appears underneath them. 

There were several reasons for editing that translation — to reflect the gender neutrality of the German more consistently; to echo Einstein's use of the words, delusion, and, illusion;  and to better reflect the certitude of the note's opening argument, carried in the brevity of the German yet somehow absent in the translation on the note itself. In the end, the edit below, supported by translations by Google on 6 March 2024, is only a minor edit of it:

Human beings are spatially and temporally limited parts of the whole that we call "universe"; yet we experience ourselves and our feelings as separate from the rest, a kind of optical delusion of our consciousness. The striving to be free of this delusion is the only object of real religion. It is not nurturing the illusion but only overcoming it which gives that measure of inner peace which is attainable.    Albert Einstein, 1950.

The translation, in pencil on the original note, became the text of the condolence letter sent from Einstein to Dr. Marcus on 12 February 1950. The first two sentences of it were then used to open the letter of condolence sent on the 4 March 1950 to Norman Salt.

A human being is a part of a whole, called by us "Universe", a part limited in time and space. He experiences himself, his thoughts and feelings as something separated from the rest — a kind of optical delusion of his consciousness. The striving to free oneself from this delusion is the one issue of pure religion, not to nourish the delusion but to try to overcome it is the way to reach the attainable measure of peace of mind.

delusions and illusions

Einstein spoke the refined German of the Bildungsbürgertum, a language characterized by its precision. It might the be reasonable to assume, as an inspection of Einstein's note also suggests, that his use of the word Täuschung (delusion) twice and Illusion once, was considered not careless.

 The German word Täuschung in the original note, meaning 'delusion' (JPG opens in a new tab).

Etymologically the word delusion implies an action, a deceiving, referring here to that suffered by human beings through our consciousness, through which we perceive a deceptive appearance, the illusion of being "separated from the rest".

Technically, delusion is a belief that, though false, has been surrendered to and accepted by the whole mind as a truth; illusion is an impression that, though false, is entertained on the recommendation of the senses or the imagination. Illusion (n.), developed in Church Latin from the late 14c. onwards to mean: a "deceptive appearance".

Although I believe that translations I have found are faithful to the originals, stripped of their context, quotations can lose much of their quality. Transliteration of punctuation, for instance, can result in an English that makes their authors sound coarse or uneducated; and 'grammatical transliterations' may substitute gender bias for the gender neutrality in an original.

Where I have edited translations it has been only in order to address issues of punctuation, prosody, and inference, that I found detracted from the content of the originals. The edits have been made with due diligence, and although I am not a professional translator or writer, I believe they are faithful, and required to make the fluency, erudition, and sensibility of the originals explicit — original texts are provided so readers may draw their own conclusions.

Footnote {delusion01a} of n_Einstein_Translation.php.

..as free-spirited and anti-bourgeois as Einstein may have appeared to be all his life, his language remained the refined German of the Bildungsbürgertum of his time, a language he mastered with virtuosity.