The mishna in Negaim which is somewhat parallel to our mishna regarding the 2 shades of white that are leprous in the Torah and the two that the Rabbis added, and elaborates a little more. The gemara explains that the mishna there doesn’t match Rabbi Akiva’s opinion as the mishna connects between Avot and Toladot and Rabbi Akiva connects between the order of the shades of white. The mishna then tries to derive from where we know Rabbi Akiva’s opinion. The first attempt is unsuccessful but the second succeeds. The gemara then explains about the different shades of the colors mentioned in the Torah. From where do we know that the verses in the Torah regarding the requirement to bring a sliding scale sin offering for an impure person relate to one who went into the mikdash or ate sacred food?