Ketubot 77A

ונכפה ⁠— כמומין שבסתר דמי. והני מילי דקביע ליה זמן, אבל לא קביע ליה ⁠— כמומין שבגלוי דמי.

And an epileptic is considered like a hidden blemish, for it is possible that nobody is aware of her ailment. The Talmud comments: And this applies only if the sickness comes at regular intervals, as the woman and her family can conceal her illness. But if the attacks do not appear at regular intervals and can occur at any time, this is considered like a visible blemish, as it is impossible that her condition is unknown to others.

מתני׳ האיש שנולדו בו מומין ⁠— אין כופין אותו להוציא. אמר רבן שמעון בן גמליאל: במה דברים אמורים ⁠— במומין הקטנים, אבל במומין הגדולים ⁠— כופין אותו להוציא.

Mishnah: In the case of a man who developed blemishes after marriage, the court does not force him to divorce his wife. Rabban Shimon ben Gamliel said: In what case is this statement said? It is said with regard to minor blemishes. However, with regard to major blemishes, which will be defined later in the Talmud, the court does force him to divorce her.

גמ׳ רב יהודה תני נולדו. חייא בר רב תני היו. מאן דאמר נולדו, כל שכן היו ⁠— (דקסברה) [דהא סברה] וקבילה. מאן דאמר היו, אבל נולדו ⁠— לא.

Talmud: Rav Yehuda teaches the Mishnah in accordance with the version quoted above: The man developed blemishes after marrying his wife. Conversely, Ḥiyya bar Rav teaches: The man had blemishes prior to the marriage. The Talmud clarifies the difference between the two opinions: The one who says that the man who developed blemishes after marriage does not have to divorce his wife says that the same halakha applies all the more so to one who had blemishes beforehand, as she was aware of them and accepted them. However, the one who says that the Mishnah is referring to one who had blemishes prior to his marriage would say that only in that case he is not compelled to divorce her, but if they developed after the marriage this is not the halakha, as she did not marry him under such conditions.