Past time is finite, future time is infinite.

The history of astronomy is a history of receding horizons.

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 outstanding feature, however, is the possibility that the velocity-distance relation may represent the de Sitter effect, and hence that numerical data may be introduced into discussions of the general curvature of space.

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

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