One of the things Boehringer points out in the earlier discussion of the Callisto myth (in the Greek chapters) is that pre-Ovid sources tend to include only fragments of the story. Or perhaps it would be more accurate to say that one of Ovid's goals was to create "definitive" versions of the myths he includes (as well as combining them into a connected and unified whole). In a previous podcast (though I forget which one at the moment) I call attention to how much of our modern view of Greek mythology comes filtered through Ovid, whereas the Greek sources--in addition to often being fragmentary--are much more diverse and contradictory.
While the image of f/f desire is at the core of the Callisto myth, that doesn't mean that any specific version of the story includes the concept of spontaneous, self-knowing desire by a woman for a woman. This is particularly true in later retellings, where Callisto may be depicted as needing to be coaxed into accepting Zeus/Artemis's embraces, or where Zeus uses the transformation only to approach Callisto and the erotic/sexual activity occurs after he returns to his male form. Or, as Boehringer notes, the entire episode of the rape may be skipped over and the story dwells only on the consequences once Callisto's pregnancy is discovered.
So it is not a stretch to see meaning in the specific version that Ovid presents, where Callisto is shown as engaging willingly and mutually in erotic kisses with someone she believes to be the goddess Artemis. They may exist in a nebulously mythic past, but they do exist in Ovid's imagination.
Boehringer, Sandra (trans. Anna Preger). 2021. Female Homosexuality in Ancient Greece and Rome. Routledge, New York. ISBN 978-0-367-74476-2
Chapter 3b: The Roman Period - Callisto in the Metamorphoses
Ovid’s major contribution to classical mythology was to bring individual stories together into a single literary work with a unified theme. As stated in the opening lines, that theme for him was “bodies changed into new forms”. When addressing the sub-theme of love, the stories included the pursuit of a desired object, impossible or forbidden loves, and the disappearance of the beloved. The individual episodes are tied together by groups of related motifs and by cross-commentary within the stories themselves. In addition to the internal structure of the stories, because they are set in a mythic past, they are used to explain and comment on the present world. Thus, the story of Callisto not only emerges from background laid out in previous episodes, but is ultimately used to explain some aspect of the world we know (i.e., the fixed nature of the constellations).
The story involves four metamorphoses: male to female and female to male (by Zeus), human to animal and earthly to celestial (Callisto and her son).
But Ovid doesn’t focus (at first) on Callisto’s backstory and context, not even providing her name until late in the story. She is described in contrast to the domestic ideal, with an emphasis on attributes specific to our to Artemis’s followers. She is a soldier, not a maiden, and the only social bond mentioned in this introduction is the one with the goddess, not a family tie as might be expected. And she is described as being in the highest faver of the goddess.
Thus: Zeus burns with desire for Callisto (a woman with masculine characteristics). Callisto and Diana have a special bond even within their woman-only society. So it seems natural for Zeus to use that bond to get inside Callisto’s defenses by taking the form of someone trusted. Yet Zeus’s purpose also requires him to take the form of someone who could approach Callisto sexually. He engages her in conversation and then kisses her: “not modestly, nor as a maiden kisses.” But when he moves on to embraces, she realizes who he is and struggles in vain against the rape.
There are several shifts in gender focus. Zeus initially is attracted to the boyish Callisto as an erastes for his eromenos—a man for a youth. But when he approaches Callisto, she has set aside her weapons and become a vulnerable girl (in how she is described). It is at this point that Zeus put on Artemis’s appearance. Starting as the desire of a god for a boy, the approach is now as a goddess for a girl, while still keeping the pederastic framing.
The erotic encounter is initially between two women and consensual. Calisto shows no surprise or hesitation in kissing one she believes to be the goddess. It is emphasized that these are not chased, modest kisses. Only when Zeus “betrays himself” in his actions does Callisto realize her partner is not Artemis and she begins to resist.
The discussion dwells on the phrase translated as “by this outrage he betrayed himself”. The phrase “sine crimine” appears nowhere else in the Metamorphoses but echoes Sappho’s line in the Heroides when she says of the women of Lesbos, “whom I have loved to my reproach”. Boehringer speculates that this is a deliberate allusion.
The encounter is full of comic references but the comedy comes from the unequal distribution of knowledge not from the sexual situation. Like other myths involving sexual identity, bathing is a context for knowledge and transformation. However in this case, it isn’t knowledge of the character’s sex that is revealed but knowledge of Callisto’s pregnancy which, in turn, was caused by Zeus’s dual sexual transformations. And unlike other stories involving a bathing Artemis and transformation, it is not an intrusive viewer who is transformed, but the person viewed: the pregnant Callisto who is then subject to Juno’s jealousy, resulting in her transformation to a bear and then to a constellation.
In contextualizing the embrace between the female Zeus/Artemis and Callisto, the author notes the overall fluidity of the mythic universe. Forms are not fixed, humans can become animals, animals become stars. Masculine and feminine intermingle. Gender is not yet tied to sex. The gender relationship between the desiring person (Zeus/Artemis) and the desired (Callisto) shifts multiple times, encompassing multiple gender modes on each side and moving from mutual and consensual to one-sided rape. But the mode in which a female lover kisses and is kissed by a female beloved is fleeting and over-written by the heterosexual outcome.
Boehringer frames this as Ovid’s explanation for the absence of this mode of love within his own (Roman) society. As with Ovid’s Sappho, he focuses on f/f love at the moment in time when it is left behind in the past.