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.

There we measure shadows, and we search among ghostly errors of measurement for landmarks that are scarcely more substantial.

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.

Astronomy is something like the ministry. No one should go into it without a call. I got that unmistakable call, and I know that even if I were second-rate or third-rate, it was astronomy that mattered.

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

Equipped with his five senses, man explores the universe around him and calls the adventure Science.