(In part 1, I offer my hypothesis: that the philosopher Spinoza, a lifelong confirmed bachelor, did not live single because he lacked opportunity, was unlucky in love or was asexual. He was gay. I review what is known for certain about his life and relationships.)

(In part 2, I discuss his writings about emotions in Book 3 of Ethics, and his declaration that “Desire is the very essence of a man,” as well as his assertion that pain, pleasure and desire are the primary emotions. This, along with his analysis of romantic love, rivalry and regret lead me to believe he’s done more than analyze these feelings; he’s lived them.)

(In part 4, I disprove one myth about Spinoza and offer a theory of my own, however unlikely it may be)

That Baruch Spinoza lived a chaste life appears to be a historical fact — whether it was by choice, lack of opportunity or simple bad luck. No letter, no personal account of his own or his friend, no official document has ever been uncovered to show that Spinoza had anything approaching a love life. At the same time, Spinoza analyzed and cataloged emotions in a way that revealed a thorough understanding of what it meant to fall in love, be in love, feel jealousy and envy and even hatred for a rival — feelings best understood by having lived through them, rather than merely observing them from the outside looking in.

That’s all well and good, but I’m well aware it’s not enough to prove my hypothesis: that Spinoza was gay. To prove that, I’ll have to wander away from the realm of what is known and what can be easily gathered from what Spinoza himself wrote and into the world of what others wrote about him, and what can be gathered by considering the way in which Spinoza moved through life in Dutch society of the middle- to late-1600s.

I’ll begin with the most solid pieces of evidence and work my way from there to the parts that take the furthest leaps of faith. Let’s begin.

Our bodies are so far apart

That’s what makes the letters between Bento and Simon de Vries, a fawning young admirer, stand out so darn much. Simon, who lived in Amsterdam when Spinoza had moved to Rijnsburg, a small town outside Leiden, was a medical student and a scion of an apparently well-to-do family (I’ll explain that in a moment). He also seems to have been the president of Spinoza’s fan club in Amsterdam. And in the winter of 1663, what Simon seems to have wanted more than anything was some time alone with Bento:

For some time now I have been anxious to visit you, but the weather and the long winter have prevented me. Sometimes I complain about my lot because the distance between us keeps us apart for so long. Your companion Casearius is very lucky to be able to live under the same roof with you, and to talk with you about important matters at breakfast, at dinner, and on your walks. But though our bodies are so far apart, you have often been present in my mind, especially when I meditate on your writings and hold them in my hands. But since not everything is clear enough to the members of our ·Amsterdam Spinoza study· group—which is why we have begun meeting again—and so that you won’t think I have forgotten you, I am writing this letter.

He then tells Spinoza — I kid you not — that this study group wasn’t sure what a “definition” was, and could Spinoza please explain? Now, I have to confess something here. I recall being a teenager and dreaming up excuses to pick up the phone and call the object of my affection, and coming up with an equally ridiculous excuse. They probably sounded as desperate as this one.

Anyway, moving on. Spinoza wrote back:

I have received your letter, which I had long looked for, and I thank you very much for it and for your feeling toward me. The length of your absence has been no less burdensome to me than to you. … There is no need for you to envy Casearius. No one is more troublesome to me, and there is no-one with whom I have to be more on my guard. So I warn you and all our friends not to communicate my views to him until he has grown up; he is still childish and unstable, more anxious for novelty than for truth. But I hope that in a few years he will correct these youthful faults. Indeed, as far as I can judge from his native ability, I am almost certain that he will. So his talent induces me to like him.

There’s a bit to unpack in this exchange beyond the extraordinary familiarity of it. First, the longing Simon expresses is, well, palpable. Like the Jewish v’ahavta prayer, Simon is evidently thinking of Bento when he lies down and when he rises up, meditating on Bento’s words and binding them as a sign upon his hand. He even addresses his friend as “master” in his letters. I swear I’m not imagining things.

But there’s a problem: a roommate, who Simon fears is a rival. As Spinoza would later write in his Ethics, “If anyone conceives that an object of his love joins itself to another with closer bonds of friendship than he himself has attained to, he will be affected with hatred towards the loved object and with envy towards his rival.” It’s not crazy to think that this could be the very (or one of the very) situations where Spinoza learned this lesson.

Spinoza writes back that Simon has no need to fear. The warm feelings between Simon and he are real and shared, and Casearius is not a rival. However, he cautions, he is a threat in another sort of way: “I have to be more on my guard. So I warn you and all our friends not to communicate my views to him until he has grown up; he is still childish and unstable, more anxious for novelty than for truth.”

What in the world does this mean? It seems odd that he would warn Simon to be cautious in telling Casearius about Spinoza’s philosophy, as no other penpal gets a similar warning. If the roommate truly was some sort of tongue-wagging spy ready to run to the predicants and denounce Spinoza as a dangerous atheist, it seems Spinoza would have sent the alarm to all his friends — but that never happened. In fact, there’s no mention of his roommate in any other letter.

What’s going on?

A man is made of his secrets

Spinoza was a notoriously secretive man. He had to be — he learned the hard way after being kicked out of the Portuguese Jewish community in Amsterdam in 1656 at the age of 23. He said at the time that the banishment didn’t do anything that he wouldn’t have chosen for himself, but it was a trick he couldn’t afford to do again. If he rose the ire of Dutch society writ large, the consequences would be so much worse. Think: prison. Think: death.

I’m not exaggerating here. Yes, Holland was famously open-minded for its time, but that had its limits. The Dutch Republic formally recognized freedom of religion, but even they drew the line at Catholicism. And atheists? That was truly pushing the line. That’s why Spinoza took the step of ensuring his Ethics would only be published posthumously.

If being godless was bad, being gay was worse. That was punishable by death. If, as I believe, Spinoza was gay, this was a secret he would have guarded with is life. Literally.

Suppose I’m right, Spinoza was a gay man in the 1600s who needed to hide the very essence of who he was. How would that color his actions? How would that determine the way he behaves? Would it change how he publicly acts toward the man he has or did have a romantic relationship with — someone like Simon de Vries?

The chain of letters between Bento and Simon was short. The first one, with Simon declaring how much he misses Bento, was by far the most passionate. Then Bento warns him off being too open in the next letter. There are two further letters sticking to matters of philosophy, each shorter. That is all we are allowed to see.

But that is not the end.

Four years later, as the unmarried and childless Simon was sick and nearing death, he wanted to name Bento his heir. The designation would come with an annuity of 500 florins (about $30,000), which is a considerable some for someone known to live near poverty. But Bento said no, turned him down. “Give it to your brother,” he said. But either Simon or his brother insisted, and Bento finally accepted an annuity of 300 florins, or $18,000.

Even $18,000 is quite a lot for someone who is “just friends.” It’s quite a bit for someone who is just “a good teacher.” Simon wanted his estate to go to the one person in the world who meant the most to him, and that one person was Bento Spinoza. The man he loved. His lover. Q.E.D.