“Technology is nature without the human being. It is abstract nature, reduced to itself, delivered over to itself, exalting and expressing itself on its own. It develops in such a way that all the virtualities and potentialities within it must be actualized, for them and for what they are, for their own sake, so that everything is done that can be done, that is to say, everything that nature can become. It is a matter of making gold, going to the moon, building self-guiding and self-monitoring missiles that can decide on the moment to self-destruction – and destroy us. Technology is alchemy; it is the self-fulfillment of nature in place of the self-fulfillment of the life that we are. It is barbarism, the new barbarism of our time, in place of culture. Inasmuch as it puts the prescriptions and regulations of life out of play, it is not simply barbarism in its most extreme and inhumane form that has ever been known – it is sheer madness.”

Letter Seven (14 May 1904)
Letters to a Young Poet (1934)
Context: People have (with the help of conventions) oriented all their solutions toward the easy and toward the easiest side of the easy; but it is clear that we must hold to what is difficult; everything alive holds to it, everything in Nature grows and defends itself in its own way and is characteristically and spontaneously itself, seeks at all costs to be so and against all opposition. We know little, but that we must hold to what is difficult is a certainty that will not forsake us; it is good to be solitary, for solitude is difficult; that something is difficult must be a reason the more for us to do it.
To love is good, too: love being difficult. For one human being to love another: that is perhaps the most difficult of all our tasks, the ultimate, the last test and proof, the work for which all other work is but preparation.

Lectures on the History of History Vol 1 p. 18 John Sibree translation (1857), 1914
Lectures on the Philosophy of History (1832), Volume 1
Context: The nature of Spirit may be understood by a glance at its direct opposite Matter. As the essence of Matter is Gravity, so, on the other hand, we may affirm that the substance, the essence of Spirit is Freedom. All will readily assent to the doctrine that Spirit, among other properties, is also endowed with Freedom; but philosophy teaches that all the qualities of Spirit exist only through Freedom; that all are but means for attaining Freedom; that all seek and produce this and this alone. It is a result of speculative Philosophy, that Freedom is the sole truth of Spirit. Matter possesses gravity in virtue of its tendency towards a central point. It is essentially composite; consisting of parts that exclude each other. It seeks its Unity; and therefore exhibits itself as self- destructive, as verging towards its opposite [an indivisible point]. If it could attain this, it would be Matter no longer, it would have perished. It strives after the realization of its Idea; for in Unity it exists ideally. Spirit, on the contrary, may be defined as that which has its center in itself. It has not a unity outside itself, but has already found it; it exists in and with itself. Matter has its essence out of itself; Spirit is self-contained existence (Bei-sich-selbst-seyn). Now this is Freedom, exactly. For if I am dependent, my being is referred to something else which I am not; I cannot exist independently of something external. I am free, on the contrary, when my existence depends upon myself. This self-contained existence of Spirit is none other than self-consciousness consciousness of one's own being. Two things must be distinguished in consciousness; first, the fact that I know; secondly, what I know. In self-consciousness these are merged in one; for Spirit knows itself. It involves an appreciation of its own nature, as also an energy enabling it to realise itself; to make itself actually that which it is potentially.

Source: The Sickness Unto Death: A Christian Psychological Exposition for Upbuilding and Awakening

Of Atheism
Essays (1625)

VIII, 35
Meditations (c. 121–180 AD), Book VIII

Das Schicksal des jüdischen Volkes ist das Schicksal Makbeths, der aus der Natur selbst trat, sich an fremde Wesen hing, und so in ihrem Dienste alles Heilige der menschlichen Natur zertreten und ermorden, von seinen Göttern (denn es waren Objekte, er war Knecht) endlich verlassen, und an seinem Glauben selbst zerschmettert werden mußte.
in Theologische Jugendschriften (1907), S. 261
The Spirit of Christianity and its Fate (1799)

Source: The Unabridged Devil's Dictionary

But philosophy has always been, and will always be, a fight with and a conquest of self-evident truths; philosophy is not looking for any "natural necessity", it sees in naturalness and in necessity alike an evil magic, which, if one cannot quite shake it off (for in this no mortal has ever yet succeeded), yet one must at least call by its right name; and even this is an important step! p. 342
Source: In Job's Balances: on the sources of the eternal truths, Words That Are Swallowed Up - Plotinus's Ecstasies

Die Natur baut keine Maschinen, keine Lokomotiven, Eisenbahnen, electric telegraphs, selfacting mules etc. Sie sind Produkte der menschlichen Industrie; natürliches Material, verwandelt in Organe des menschlichen Willens über die Natur oder seiner Betätigung in der Natur. Sie sind von der menschlichen Hand geschaffene Organe des menschlichen Hirns; vergegenständliche Wissenskraft. Die Entwicklung des capital fixe zeigt an, bis zu welchem Grade das allgemeine gesellschaftliche Wissen, knowledge, zur unmittelbaren Produktivkraft geworden ist und daher die Bedingungen des gesellschaftlichen Lebensprozesses selbst unter die Kontrolle des general intellect gekommen, und ihm gemäß umgeschaffen sind.
(1857/58)
Source: Notebook VII, The Chapter on Capital, p. 626.