Observation always involves theory.

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.

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.

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

Not until the empirical resources are exhausted, need we pass on to the dreamy realms of speculation.

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.