1) THE DIFFICULTY OF THE ACT OF CHAFINAH
OPINIONS: The Gemara describes Chafinah as one of the most difficult Avodos performed in the Beis ha'Mikdash. When the Kohen Gadol entered the Kodesh ha'Kodashim to burn the special incense of Yom Kippur, he carried the Kaf containing the Ketores in his left hand and a pan of burning coals in his right hand. He placed the pan of coals on the floor, poured the Ketores from the Kaf into his palms and spread the Ketores on the coals, as the verse instructs (Vayikra 16:12-13).
The difficulty is the act of pouring the Ketores into the hands. Since the Kohen Gadol held the Kaf with one hand, how did he pour the Ketores from there into both of his hands?
(a) RASHI (as explained in more detail by the ME'IRI on the Mishnah) explains that the Kohen Gadol held the Kaf in his hands and used his thumbs to slide the handle of the Kaf back towards his body until it was positioned between his elbows, with the edge of bowl-part of the Kaf in his fingertips (and the bowl resting on the fleshy part of the palm). Then, with the help of his elbows, he rotated the bowl above his hands and emptied the Ketores into his palms, all the while being careful not to spill any of it.
(b) According to the RAMBAM (Hilchos Avodas Yom ha'Kipurim 4:1), whose text of the Gemara here was slightly different, the Kohen Gadol tilted the Kaf up above his hands with his fingertips or teeth, and then swept the Ketores into his palms with his thumbs.
(c) Both Rashi's description and the Rambam's description of the act of Chafinah are based on the words of the Gemara here. The Yerushalmi (Yoma 5:2), however, records two other suggestions for how the Chafinah was done. Rebbi Chaninah says that the Kohen Gadol threw the Kaf into the air so that it flipped over, and he caught the falling Ketores in his two hands. Shmuel says that he placed the handle of the Kaf between his legs and then rotated it so that the Ketores emptied into his hands. (This is similar to Rashi's explanation, except that the Kohen Gadol used his legs instead of his elbows to help rotate the Kaf.)