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.

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

Past time is finite, future time is infinite.

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

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.

Observations always involve theory.