To the man of science, on his unassuming and laborious travels, which must often enough be journeys through the desert, there appear those glittering mirages called 'philosophical systems'; with bewitching deceptive power they show the solution of all enigmas and the freshest draught of the true water of life to be near at hand; his heart rejoices, and it seems to the weary traveller that his lips already touch the goal of all the perseverance and sorrows of the scientific life... Other natures again, may well grow exceedingly ill-humoured and curse the salty taste which these apparitions leave behind in the mouth and from which arises a raging thirst – without one having been brought so much as a step nearer to any kind of spring.