“It is said that "being" is the most universal and the emptiest concept. As such it resists every attempt at definition. Nor does this most universal and thus indefinable concept need any definition. Everybody uses it constantly and also already understands what is meant by it.”

Boas (1928) in foreword to Margaret Mead (1928) Coming of Age in Samoa.

Source: 1970s, Organizational Analysis: A Sociological View, 1970, p. 133

1910s, The Problems of Philosophy (1912)

Quoted from Elst, Koenraad (2002). Who is a Hindu?: Hindu revivalist views of Animism, Buddhism, Sikhism, and other offshoots of Hinduism. ISBN 978-8185990743, with quote from Ambedkar: The Buddha and his Dhamma, 1:5:2.

Source: Gravity and Grace (1947), p. 129 (1972 edition)

From Kant to Hilbert (1996)
Context: Mathematics is in its development entirely free and is only bound in the self-evident respect that its concepts must both be consistent with each other, and also stand in exact relationships, ordered by definitions, to those concepts which have previously been introduced and are already at hand and established. In particular, in the introduction of new numbers, it is only obligated to give definitions of them which will bestow such a determinacy and, in certain circumstances, such a relationship to the other numbers that they can in any given instance be precisely distinguished. As soon as a number satisfies all these conditions, it can and must be regarded in mathematics as existent and real.

Source: The Financier (1912), Ch. XIII

Negative Dialektik ... handelt sich um den Entwurf einer Philosophie, die nicht den Begriff der Identität von Sein und Denken voraussetzt und auch nicht in ihm terminiert, sondern die gerade das Gegenteil, also das Auseinanderweisen von Begriff und Sache, von Subjekt und Objekt, und ihre Unversöhntheit, artikulieren will.
Source: Lectures on Negative Dialectics (1965-66), p. 6

Source: Why Stock Markets Crash - Critical Events in Complex Systems (2003), Chapter 2, Fundamentals Of Financial Markets, p. 38.