Speaking of the Enlightenment, I think my favorite among the Nietzsche books I've completed in my current re-reading process is Human, All Too Human, which is the work of his that is most closely connected with the Enlightenment. This connection is best explicated, I think, in the following entries:
A delusion in the theory of revolution. -- There are political and social fantasists who with fiery eloquence invite a revolutionary overturning of all social orders in the belief that the proudest temple of fair humanity will then at once rise up as though of its own accord. In these perilous dreams there is still an echo of Rousseau's superstition, which believes in a miraculous, primeval, but as it were buried goodness of human nature and ascribes all the blame for this burying to the institutions of culture in the form of society, state, and education. The experiences of history have taught us, unfortunately, that every such revolution brings about the resurrection of the most savage energies in the shape of the long-buried dreadfulness and excesses of the most distant ages: that a revolution can thus be a source of energy in a mankind grown feeble, but never a regulator, architect, artist, perfector of human nature. -- It is not Voltaire's moderate nature, inclined as it was to ordering, purifying, and reconstructing, but Rousseau's passionate follies and half-lies that called forth the optimistic spirit of the Revolution against which I cry: 'Ecrasez l'infame!' [Crush the infamy!] It is this spirit that has for a long time banished the spirit of the Enlightenment and of progressive evolution: let us see -- each of us within himself -- whether it is possible to call it back! (Volume I, §463)
The perilousness of the Enlightenment. -- All the semi-insanity, histrionicism, bestial cruelty, voluptuousness, and especially sentimentality and self-intoxication, which taken together constitutes the actual substance of the Revolution and had, before the Revolution, become flesh and spirit in Rousseau -- this creature then went on with perfidious enthusiasm to set the Enlightenment too on its fanatical head, which thereby itself began to glow as though in a transfigured light: the Enlightenment, which is fundamentally so alien to the Revolution and, left to itself, would have passed quietly along like a gleam in the clouds and for long been content to address itself only to the individual, so that it would have transformed the customs and institutions of nations only very slowly. Now, however, tied to a violent and impulsive companion, the Enlightenment itself became violent and impulsive. Its perilousness has thereby become almost greater than the liberating illumination it brought to the great revolutionary movement. He who grasps this will also know out of what compound it has to be extracted, of what impurity it has to be cleansed: so as then to continue the work of the Enlightenment in himself, and to strangle the Revolution at birth, to make it not happen. (Volume II, Part 2, §221)
For Nietzsche, then, Enlightenment is above all a personal matter: it works quietly, progressively, internally, out of sight; it is alien to mass movements; it is nearly impervious to revolutionary sentiments and radical manifestos; it is a matter not for collective action but for individual cultivation.
Cultivation. It is no coincidence that Human, All Too Human is steeped in the Epicurean imagery of tending one's own garden, of looking at the world with clear eyes, of pruning one's hopes but plucking the day (Horace Odes I.11), of living "happily and peaceably with oneself even in the turmoil of life" (Volume I, §626), of simple and moderate pleasures, of that serenity which Epicurus called ataraxia. Has anyone written at length on Nietzsche and Epicurus? I sense the need for a comparative study.