“As knowledge increases, the verdict of yesterday must be reversed today, and in the long run the most positive authority is the least to be trusted.”

“The clock is running. Make the most of today. Time waits for no man. Yesterday is history. Tomorrow is a mystery. Today is a gift. That's why it is called the present.”

“You cannot win today's ballgame with yesterday's home runs.”

“There is the authority of position and the authority of knowledge - 'Authority flows from the one who knows.' But sharing in hardship confers upon a leader something quite rare - moral authority.”

“Thought as such… is an act of negation, of resistance to that which is forced upon it; this is what thought has inherited from its archetype, the relation between labor and material. Today, when ideologues tend more than ever to encourage thought to be positive, they cleverly note that positivity runs precisely counter to thought, and that it takes friendly persuasion by social authority to accustom thought to positivity.”

“One of the most incredible secrets of science fiction (although one not too closely guarded) is the fact that 99 percent of its authors do not know even the titles and authors of today's learned works, but still they want to top these scholars with their knowledge of the year 6000.”