They are ill discoverers that think there is no land, when they can see nothing but sea.

Francis Bacon (1561-1626) English philosopher, scientist, author, statesman

De Augmentis Scientiarum [Advancement of Learning], Book 3, ch. 4 (1605)
    (Source)

Alt trans: "[They] are indolent discoverers who seeing nothing beyond but sea and sky, absolutely deny there can be any land beyond them."

Another source notes it as Book 2, ch. 7.