The history of astronomy is a history of receding horizons.

Science is the one human activity that is truly progressive. The body of positive knowledge is transmitted from generation to generation.

The great spirals... apparently lie outside our stellar system.

Past time is finite, future time is infinite.

A scientist naturally and inevitably ... mulls over the data and guesses at a solution. He proceeds to testing of the guess by new data-predicting the consequences of the guess and then dispassionately inquiring whether or not the predictions are verified.

Wisdom cannot be directly transmitted, and does not readily accumulate through the ages.

The universe is unfolding as it should.