The weak points of this philosophy, the mistaken aim and incomplete method of enquiry, the real ignorance of facts disguised under an appearance of systematic treatment, the unproductiveness of the results for any practical accession to man's power over Nature, are quite obvious to any modern reader, who, without any special study of physical science, cannot help being familiar with information which is now universally diffused, but which was beyond the reach of the most ardent enquirers and original thinkers of antiquity.
"The Roman Poets of the Republic"
W. Y. Sellar
Their intellectual poverty condemns them to unproductiveness; nevertheless, being nearer than the others to the imaginative type, they bring forth childish or chimerical productions.
"Essay on the Creative Imagination"
Th. Ribot
Inventors, great and small, never cease to complain over the periods of unproductiveness which they undergo in spite of themselves.
"Essay on the Creative Imagination"
Th. Ribot