History
History (from Greek ἱστορία, historia, meaning "inquiry, knowledge acquired by investigation") is the study of the past as it is described in written documents. Events occurring before written record are considered prehistory. It is an umbrella term that relates to past events as well as the memory, discovery, collection, organization, presentation, and interpretation of information about these events. Scholars who write about history are called historians.
Literature
Literature, most generically, is any body of written works. More restrictively, literature writing is considered to be an art form, or any single writing deemed to have artistic or intellectual value, often due to deploying language in ways that differ from ordinary usage.
Present
The present (or here and now) is the time that is associated with the events perceived directly and in the first time, not as a recollection (perceived more than once) or a speculation (predicted, hypothesis, uncertain). It is a period of time between the past and the future, and can vary in meaning from being an instant to a day or longer. In radiocarbon dating, the "present" is defined as AD 1950.
Theory
A theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context, the results might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings.
Theory
All men suppose what is called Wisdom to deal with the first causes and the principles of things; so that, as has been said before, the man of experience is thought to be wiser than the possessors of any sense-perception whatever, the artist wiser than the men of experience, the masterworker than the mechanic, and the theoretical kinds of knowledge to be more of the nature of Wisdom than the productive.
Aristotle, Metaphysics, 982a1, Complete Works, vol. 2, p. 1553
Theory
Practical life is not necessarily directed toward other people, as some think; and it is not the case that practical thoughts are only those which result from action for the sake of what ensues. On the contrary, much more practical are those mental activities and reflections which have their goal in themselves and take place for their own sake.
Aristotle, Politics, VII, 3, 8, 1325b16-20
Theory
A theory is the more impressive the greater the simplicity of its premises is, the more different kinds of things it relates, and the more extended its area of applicability.
Albert Einstein, "Autobiographical Notes," in Albert Einstein: Philosopher-Scientist, P. Schlipp, ed. (Cambridge University Press, London: 1949), p. 33
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