Our ideas are only partly our ideas. Most of our ideas are abbreviations or residues of the thought of other people, of our teachers (in the broadest sense of the term) and of our teachers' teachers; they are abbreviations and residues of the thought of the past. These thoughts were once explicit and in the center of consideration and discussion. It may even be presumed that they were once perfectly lucid. By being transmitted to later generations they have possibly been transformed, and there is no certainty that the transformation was effected consciously and with full clarity. … This means that the clarification of our political ideas insensibly changes into and becomes indistinguishable from the history of political ideas.

p. 73 - What is Political Philosophy (1959)