Rejected by his Jewish community in Amsterdam, Baruch Spinoza was living alone in a small village outside The Hague in Holland and earning his living by grinding lenses when he wrote one of the most renowned works of modern philosophy. Spinoza’s Ethics laid foundations for the Enlightenment by proposing a humane rationalism that left room for intuition and religious belief, in contrast to the more austere thinking of René Descartes.

Ethics was published in the year of Spinoza’s death, 1677, and he knew it would cause controversy. He sought to employ mathematical rigor to disprove the existence of a sentient god. For good measure, he denied the existence of good and evil in an absolute sense, saying they are only interpretations that we put on our desires. He reasoned that emotional investment in past traumas or in future hopes and fears is irrational because they are only products of our artificial conception of time. He argued contrary to Descartes, who was his greatest influence, that the mind and body are not mutually independent like the controller and a machine, but are inextricably bound up with one another, such that there are forms of knowledge that can be said to be embodied – held within the body, not only the mind. He further considered the ways in which we gain knowledge, identifying three routes – by random experience, by invoking the nature of a thing from words, memories, and comparison with things already known, and by intuitively grasping the essence of a thing.

These ideas have found their place in the philosophical canon. But what was the background that encouraged Spinoza to nurture these so humane, and yet at the time so revolutionary, thoughts?


Spinoza was small in stature, with black eyes, black hair, and a ‘beautiful face’, in all ‘a good-looking young man, with an unmistakably Mediterranean appearance’, according to the monk who left us the best contemporary description of him. As Sephardic Jews, his family had fled from Spain to Portugal, and then, when the Inquisition pursued them, to the Dutch Republic, where Baruch was born in 1632, and spent the entirety of his quiet life. By his virtuous life and work, he became the man Bertrand Russell calls ‘the noblest and most lovable of the great philosophers’.

He made his modest daily living as a lens grinder, a craft he probably learned while still in Amsterdam. It stood him in good stead when he moved away and was able to sustain himself by making lenses for the new optical instruments – the telescopes and microscopes of gentleman scientists, camera obscuras for artists, as well as lenses for spectacles. He became very good at it, and his wares were sought after by leading astronomers. The Huygens brothers, Constantijn and Christiaan, astronomers who made their own telescopes and lenses, nevertheless prized Spinoza’s lenses above those of other makers.

Spinoza’s profession was not simply a matter of commercial necessity. He also, like his mentor Descartes, wrote treatises on physical phenomena, such as the rainbow. The emerging science of optics, dealing as it did with reality at the scale of the cosmos and the microcosm and with what was perceivable and true, was intimately linked with the philosophical theory of the time.

Lens makers work by shaping pieces of glass, which must be clear and without bubbles or other flaws, in grinding dishes curved according to the focal length of lens that they want to produce. The dishes are spun on a lathe, while various grinding compounds are used to shape and polish the glass surface. It was, according to Spinoza’s biographer, Steven Nadler, ‘a quiet, intense, and solitary occupation, demanding discipline and patience – in a word, an occupation perfectly suited to Spinoza’s temperament.’

The eternity of the mind

Might this routine work actually have shaped Spinoza’s philosophical ideas? First, consider the third of his three kinds of knowledge. It is a bold step to say that we can learn by simply grasping the essence of a thing, but more bold for an ‘armchair’ philosopher to posit this, than one whose hands are engaged in close physical labour that alters the appearance of substance.

Second, in his ‘proof’ inspired by the methods of geometry, Spinoza asserts that God cannot stand outside nature, and so must be in nature and in all of nature. To the extent that God exists, God is nature. Our bodies are subject to the laws of nature – again, something that might easily be appreciated by working at a lathe – and knowing this frees us from evil passions and fear of God.

For Spinoza, expert knowledge is something that is possessed not only in the mind but also in the body. ‘Thus,’ according to Aristides Baltas, a philosopher of science (and recent Greek minister of culture), ‘expert action manifests the merger of mind and body and displays how this merging works: a body-mind, that is, a person as body-mind, knows on his or her own, by his or her inseparable body and mind, what the body should do and what the mind should do and how to act with both as inseparable.’ Watching craftspeople at work, it is easy to appreciate this from the tactile feedback they obtain as they form an object. It is as if the eyes can see through the shaping fingers.

With large-scale objects fashioned for aesthetic reasons, this sense transference continues in the life of the object. By touching the object ourselves we experience a vicarious human contact with the maker whose touch fashioned it in the first place. We perhaps even feel privileged to obtain an insight into that maker’s vision. This is not so important in the case of Spinoza’s lenses, which were very small, and fashioned for more utilitarian purposes. Nevertheless, Spinoza chose to grind his lenses manually, bringing the glass into contact with the grinding surface using his hand. There is evidence that he preferred this basic but more tactile method, because he rejected a more automated process used by Huygens.

Working in unreal time

Third, Spinoza ‘regards time as unreal’, as Bertrand Russell puts it. This is surely another realization stimulated by the sensations of his work. People intensely engaged in a task are often said to ‘lose themselves’ in their work. In The Craftsman, the sociologist Richard Sennett writes of how craft workers lose self-awareness and in a sense merge with the object they are making: ‘We have become the thing on which we are working.’

‘Successfully performing an activity with wholly undivided purpose on the basis of expert knowledge – devoting oneself fully to this activity and executing all the actions making it up both expertly and fully – is invariably accompanied by a feeling of being at one both with oneself and with the world at large,’ writes Baltas in his study of Spinoza. ‘On the one hand, the expert’s body and mind have worked in perfect unison, manifesting thereby that person’s whole and undivided nature both to the actor him- or herself and to everybody concerned; on the other hand, success demonstrates that the expert has taken in the world as it really is and hence that he or she has been in full harmony with it.’

Aside from the crafted object, the result of this process for the maker is a profound sense of satisfaction that infuses both body and mind – a ‘feeling that,’ as Baltas puts it, ‘he or she has fully lived the moment of success as a present moment, the feeling, precisely, of having experienced eternity.’ This surely informs Spinoza’s doctrine of ‘the eternity of the mind’ – the idea that mind exists outside of time.

It materializes the sense of a ‘job well done’, where hand, head, and heart have worked together. One might add that in the case of a perfectly shaped lens, the maker is now able to see more clearly. He or she has literally brought the world into focus.

In the physical world, Spinoza’s task was to bring lumps of glass to perfection as lenses. In the metaphysical, his great achievement was to articulate a compelling philosophy of virtue, based on the idea that human beings lack free will, but that nevertheless we believe we possess it.

Spinoza’s routine procedure involving intense concentration was surely essential for both tasks. It allowed the mind to work on twin tracks, one focused on the manual task governed by hand–eye coordination and the central nervous system, the other free to roam landscapes of intellectual possibility. It may have contributed to specific insights, such as intuited essence, the embodied mind, and the mind out of time. (Of course, other great philosophers were not lens grinders, or makers of any sort, although Wittgenstein once said he worked best when peeling potatoes.)

Knowing about this immensely patient and painstaking work, it is less of a wonder that Spinoza developed not only an equable personal temperament but also a philosophy strongly dependent on the idea of living in the moment. More practically, this employment also had the advantage that Spinoza was able to decline a professorial position that might have set boundaries on what it was permitted to think.

In a broader sense, too, skill and ethics are closely bound together. We should not be surprised at this. There is a fundamental honesty required to work with materials and transform them. But all sorts of manual tasks, ranging well beyond standard definitions of craft and making – baking bread, assaying metals, or truthfully recording the results of scientific experiments, for example – depend upon such a connection. If only activities such as politics and banking did too.


Baltas, Aristides, Peeling Potatoes or Grinding Lenses: Spinoza and Young Wittgenstein Converse on Immanence and its Logic (Pittsburgh: University of Pittsburgh Press, 2012)

Nadler, Steven, Spinoza: A Life (Cambridge: Cambridge University Press, 1999)

Russell, Bertrand, History of Western Philosophy (London: Routledge, 2015)

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