Shevuos Daf 6 חג השבועות דַף 6

In a Baraisa, Rebbe Yehoshua the son of Rebbe Akiva asked his father: מפני מה אמרו מראות נגעים שנים שהן ארבעה – Why did they say, “Appearances of tzaraas are two which are four”? Rebbe Akiva asked him what they should have said instead, and Rebbe Yehoshua explained they should have said: מקרום ביצה ולמעלה טמא – “any shade of white from egg membrane and above is tamei.” Rebbe Akiva answered that they listed the four shades in a specific order, לומר שמצטרפים זה עם זה – to say that they combine with each other according to the order taught. Rebbe Yehoshua persisted that they could have taught, “Any shade of white from קרום ביצה and above is tamei, and they combine with each other,” and Rebbe Akiva answered that they taught the list of four shades of tzaraas to teach: כל כהן שאינו בקי בהן ובשמותיהן אינו רואה את הנגעים – any Kohen who is not an expert in identifying them and their names may not examine tzaraas.

The Gemara seeks to prove that Rebbe Akiva lists the four shades of נגעים (to combine) in order of whiteness. After the first proof is rejected, the Gemara quotes Chanina, who says Rebbe Akiva’s opinion is analogous to ארבעה כוסות של חלב – four cups of milk, אחד נפלו לתוכו שתי טיפין של דם – into one of which fell two drops of blood, into another fell four drops of blood (darkening it slightly more), into another fell eight drops, and into the fourth fell twelve (or sixteen) drops. שכולן מראות לובן הן – For all of them are shades of white, אלא שזה למעלה מזה וזה למעלה מזה – except that this one is above (whiter than) this one, and this one is above this one. This proves that Rebbe Akiva’s list for combining the four shades is in order of intensity. The Gemara asks that perhaps Rebbe Akiva only holds this way regarding פתוך – a mixed spot (reddish-tinged), but not regarding חלוק – pure white spots? It responds that we can assume that he holds the same way regarding pure white spots. A counterproof is brought from a Mishnah but is deflected.

Abaye says that we know בהרת is the most intense white because the passuk, "אם בהרת לבנה היא" – and if it is a white baheres, teaches: היא לבנה ואין אחרת לבנה – it is truly white, and no other shade is truly white. A Baraisa states: בהרת עמוקה – a baheres spot appears deeper than the nearby skin because of its intense whiteness, as the passuk says: ומראה עמוק מן העור – and its appearance is deeper than the skin, meaning: כמראה חמה העמוקה מן הצל – like the appearance of the sun, which is deeper than the nearby shade. The word "שאת" is explained: אין שאת אלא גבוה – se’eis [implies] nothing but “raised,” (i.e., less intensely white), as in the phrase "כל הגבעות הנשאות" –  all the raised-up hills. The next word, "ספחת", implies טפילה – subordinate, as the passuk says: ואמר ספחני נא – and he will say, “Please attach me…” The Gemara asks how we know that בהרת also has a "טפילה" (i.e., תולדה). Rebbe Zeira says that since "לבנה" – white is written both regarding בהרת and שאת, we derive that just as שאת has a טפילה, so too בהרת has a טפילה. A Baraisa teaches that the word "ספחת" was written between שאת and בהרת to teach that just as שאת has a טפילה, so too בהרת has a טפילה.