The joy of discovery is certainly the liveliest that the mind of man can ever feel.

When entering on new ground we must not be afraid to express even risky ideas so as to stimulate research in all directions. As Priestley put it, we must not remain inactive through false modesty based on fear of being mistaken.

A fact in itself is nothing. It is valuable only for the idea attached to it, or for the proof which it furnishes.

The investigator should have a robust faith - and yet not believe.

A contemporary poet has characterized this sense of the personality of art and of the impersonality of science in these words,-'Art is myself; science is ourselves. '

Priestley [said] that each discovery we make shows us many others that should be made.

Science does not permit exceptions.