Philosophy as practice does not mean its restriction to utility or applicability, that is, to what serves morality or produces serenity of soul.

The great philosophers and the great works are standards for the selection of what is essential. Everything that we do in studying the history of philosophy ultimately serves their better understanding.

The 'public' is a phantom, the phantom of an opinion supposed to exist in a vast number of persons who have no effective interrelation and though the opinion is not effectively present in the units. Such an opinion is spoken of as 'public opinion,' a fiction which is appealed to by individuals and by groups as supporting their special views. It is impalpable, illusory, transient; "'tis here, 'tis there, 'tis gone"; a nullity which can nevertheless for a moment endow the multitude with power to uplift or destroy.

At the present moment, the security of coherent philosophy, which existed from Parmenides to Hegel, is lost.

Just as primitive man believed himself to stand face to face with demons and believed that could he but know their names he would become their master, so is contemporary man faced by this incomprehensible, which disorders his calculations.

An ideology is a complex of ideas or notions which represents itself to the thinker as an absolute truth for the interpretation of the world and his situation within it; it leads the thinker to accomplish an act of self-deception for the purpose of justification, obfuscation and evasion in some sense or other to his advantage.

Man is always something more than what he knows of himself. He is not what he is simply once and for all, but is a process; he is not merely an extant life, but is, within that life, endowed with possibilities through the freedom he possesses to make of himself what he will by the activities on which he decides.