אֵין רוֹאִים הַנְּגָעִים בַּשַּׁחֲרִית וּבֵין הָעַרְבַּיִם, וְלֹא בְתוֹךְ הַבַּיִת, וְלֹא בַיּוֹם הַמְעֻנָּן, לְפִי שֶׁהַכֵּהָה נִרְאֵית עַזָּה. וְלֹא בַצָּהֳרַיִם, לְפִי שֶׁעַזָּה נִרְאֵית כֵּהָה. אֵימָתַי רוֹאִין. בְּשָׁלשׁ, בְּאַרְבַּע, וּבְחָמֵשׁ, וּבְשֶׁבַע, וּבִשְׁמֹנֶה, וּבְתֵשַׁע, דִּבְרֵי רַבִּי מֵאִיר. רַבִּי יְהוּדָה אוֹמֵר, בְּאַרְבַּע, בְּחָמֵשׁ, בִּשְׁמֹנֶה, וּבְתֵשַׁע:
Negaim may not be inspected in the early morning or in the evening, nor in a house, nor on a cloudy day, because then the dull white appears like bright white; nor may they be inspected at noon, because then the bright white appears like dull white. When are they to be inspected? During the third, fourth, fifth, eighth or ninth hour, the words of Rebbi Meir. Rebbi Yehudah ruled: during the fourth, fifth, eighth or ninth hour.
[Negaim 2-2]
Let's say the Kohen KNOWS that he won't make a mistake. He has seen this type of nega a hundred times. Can he examine it??
What is the שורש המחלוקת between R' Meir and R' Yehuda? Is it a מחלוקת in the מציאות??
