At the last dim horizon, we ...

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.
 Edwin Powell Hubble

Quotes from the same author

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