for Plato and the older philosophers, time is the enemy of man. [Footnote:  The quotations and the references here will be found in Nat.  Quaest. i.  Praef.; Epist. 104, Sec. 16 (cp. 110, Sec. 8; 117, Sec. 20, and the fine passage in 65, Sec. 16-21); Nat.  Quaest. iii. 28-30; and finally Epist. 90, Sec. 45, cp.  Sec. 17.  This last letter is a criticism on Posidonius, who asserted that the arts invented in primitive times were due to philosophers.  Seneca repudiates this view:  omnia enim ista sagacitas hominum, non sapientia inuenit.

Seneca touches on the possibility of the discovery of new lands beyond the ocean in a passage in his Medea (374 sqq.) which has been often quoted: 

        uenient annis
 secula seris, quibus oceanus
 uincula rerum laxet et ingens
 pateat tellus Tiphysque novos
 detegat orbes, ...
 nec sit terris ultima Thule.]

4.

There was however a school of philosophical speculation, which might have led to the foundation of a theory of Progress, if the historical outlook of the Greeks had been larger and if their temper had been different.  The Atomic theory of Democritus seems to us now, in many ways, the most wonderful achievement of Greek thought, but it had a small range of influence in Greece, and would have had less if it had not convinced the brilliant mind of Epicurus.  The Epicureans developed it, and it may be that the views which they put forward as to the history of the human race are mainly their own superstructure.  These philosophers rejected entirely the doctrine of a Golden Age and a subsequent degeneration, which was manifestly incompatible with their theory that the world was mechanically formed from atoms without the intervention of a Deity.  For them, the earliest condition of men resembled that of the beasts, and from this primitive and miserable condition they laboriously reached the existing state of civilisation, not by external guidance or as a consequence of some initial design, but simply by the exercise of human intelligence throughout a long period. [Footnote:  Lucretius v. 1448 sqq. (where the word progress is pronounced): 

 Usus et impigrae simul experientia mentis
 Paulatim docuit pedetemtim progredientis. 
 Sic unum quicquid paulatim protrahit aetas
 In medium ratioque in luminis erigit oras. 
 Namque alid ex alio clarescere et ordine debet
 Artibus, ad summum donee uenere cacumen.]

The gradual amelioration of their existence was marked by the discovery of fire and the use of metals, the invention of language, the invention of weaving, the growth of arts and industries, navigation, the development of family life, the establishment of social order by means of kings, magistrates, laws, the foundation of cities.  The last great step in the amelioration of life, according to Lucretius, was the illuminating philosophy of Epicurus, who dispelled the fear of invisible powers and guided man from intellectual darkness to light.