The history of astronomy is a history of receding horizons.

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.

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

Past time is finite, future time is infinite.

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

Equipped with our five senses - along with telescopes and microscopes and mass spectrometers and seismographs and magnetometers and particle accelerators and detectors sensitive to the entire electromagnetic spectrum - we explore the universe around us and call the adventure science.