The history of astronomy is a history of receding horizons.

At the last dim horizon, we search among ghostly errors of observations for landmarks that are scarcely more substantial. The search will continue. The urge is older than history. It is not satisfied and it will not be oppressed.

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

The universe is unfolding as it should.

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.

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

All nature is a vast symbolism: Every material fact has sheathed within it a spiritual truth.