I have dwelt upon these geological incidents so fully, because nowhere does one realise the striking contrast between the shortness of man's existence on earth, as in places like the Roman plain, where the traces of cosmical energy have been greatest and most enduring. The volcanic origin of the Roman Forum suggests the curious idea of the intimate connection of some of the greatest events of history with volcanic centres. Where the strife of nature has been fiercest, there by a strange coincidence the storm of human passion has been greatest. The geological history of a region is most frequently typical of its human history. We can predicate of a scene where the cosmical disturbance has been great,--where fire and flood have contended for the mastery, leaving the effects of their strife in deepening valleys and ascending hills,--that there man has had a strangely varied and eventful career. The strongholds and citadels of the earth, where the great battles of freedom and civilisation have been fought, were all untold ages previously the centres of violent plutonic disturbances. Edinburgh Castle, enthroned on its trap-rock, once the centre of a volcano, is associated with the most stirring and important events in the history of Scotland; Stirling Castle rises on its trap-rock erupted by volcanic action above a vast plain, across which a hundred battles have swept; Dumbarton Castle, crowning its trappean promontory, has represented in its civil history the protracted periods of earthquake and eruption concerned in the formation of its site; while standing in solitude amid the stormy waters of the Firth of Forth, the Bass Rock, once a scene of fiery confusion, of roaring waves and heaving earthquakes, has formed alternately the prison where religious liberty has been strangled, and the fortress where patriotism has taken its last stand against the forces of the invader. Palestine, Greece, Italy, Switzerland, and Scotland, the countries that have had the most remarkable history, and have done most to advance the human race, are distinguished above other countries for their geological convulsions and revolutions. The Roman Forum is thus but one specimen among numerous others of a law of Providence which has associated the strife of nature with the strife of man, and caused the ravages of the most terrible elements to prepare the way for the highest development of the human race.