Indeed, the attentive study of the fine abstractions of science lifts the mind from the grossness of matter, step by step, to the refinements of immateriality, and there appear, shadowed out beyond the physical forces which man can test and try, other powers still ascending, until they reach the Source of every good and every perfect gift. FOOTNOTES: [84] “These--oxygen, hydrogen, nitrogen, and carbon--are the four bodies, in fact, which, becoming animated at the fire of the sun, the true torch of Prometheus, approve themselves upon the earth the eternal agents of organisation, of sensation, of motion and of thought.”--Dumas, _Leçons de Philosophie Chimique_, p. 100. Paris, 1837. [85] It will be found in examining any of the works of the alchemists,--particularly those of Geber, _De inveniendi arte Auri et Argenti_, and his _De Alchemiâ_; Roger Bacon’s _Opus Majus, or Alchymia Major_; Helvetius’ _Brief of the Golden Calf_; or Basil Valentine’s _Currus Triumphalis_,--that in the processes of transmutation the solar light was supposed to be marvellously effective. In Boyle’s _Sceptical Chemist_ the same idea will be found pervading it. Amid all their errors, the alchemists were assiduous workmen, and to them we are indebted for numerous facts. Of them, and of their age, as contrasted with our own, Gibbon remarks:--“Congenial to the avarice of the human heart, it was studied in China, as in Europe, with equal eagerness and equal success. The darkness of the middle ages ensured a favourable reception to every tale of wonder; and the revival of learning gave new vigour to hope, and suggested more specious arts of deception. Philosophy, with the aid of experience, has at length banished the study of alchemy; and the present age, however desirous of riches, is content to seek them by the humbler means of commerce and industry.”--_Decline and Fall_, vol. ii. p. 137. [86] On the two theories the following maybe consulted:--Young, _Supplement to Encyclopædia Britannica_, article _Chromatics_; Fresnel, _Supplément à la Traduction Française de la 5ième édition du Traité de Chimie de Thomson_, par Riffault, Paris, 1822; Herschel’s Article, _Light_, in the Encyclopædia Metropolitana, and the French Translation of it by Quetelet and Verhulst; Airy’s _Tract on the Undulatory Theory_, in his Tracts, 2nd edition, Cambridge, 1831; Powel, _The Undulatory Theory applied to Dispersion_, &c. p. 184; Lloyd’s _Lectures_, Dublin, 1836-41; Cauchy, _Sur le Mouvement des Corps élastiques_, Mémoires de l’Institut, 1827, vol. ix. p. 114; _Théorie de la Lumière_, Ibid. vol. x. p. 293; M’Cullagh, _On Double Refraction_, Ibid., vol. xvi.; _Geometrical Propositions applied to the Wave Theory of Light_, Ibid., vol. xvii.; Sir David Brewster’s papers in the Transactions of the Royal Society of Edinburgh, and the Philosophical Magazine.