A baby is born with the soul level of Nefesh that connects the body to the basic state of life in Malchut, the world of Asiah, Action. At the circumcision the child receives a blessing with a name that represents his soul. The light of the level of Nefesh is awakened on the child and make him ready for his future. When the child grows to study the Torah, he receives the light of Ruach from the world of Yetzirah, ‘Formation’. When he follows the ways of the Torah he receives the light of Neshama from the world of Briah, ‘Creation’. After he gets married and have children educated in the ways of Torah he receives light of Chaya from the world of Atziluth, ‘Emanation’. Achieving all four levels making that person complete.
“שׁוֹר אוֹ כֶשֶׂב אוֹ עֵז כִּי יִוָּלֵד וְהָיָה שִׁבְעַת יָמִים תַּחַת אִמּוֹ וּמִיּוֹם הַשְּׁמִינִי וָהָלְאָה יֵרָצֶה לְקָרְבַּן אִשֶּׁה לַיהוָה”
“When an ox or a sheep or a goat is born, it shall remain seven days with its mother, and from the eighth day on it shall be accepted as a sacrifice of an offering by fire to YHVH”
‘When an ox or a sheep or a goat is born’. The animals are described in their grown up form even though the verse says ‘when… is born’ and should refer to the animal in its first state. It should read calf instead of ox, A lamb instead of sheep, a kid instead goat.
The Zohar explains that animals have the same life force when they were born and die. They don’t have spiritual abilities to change their souls. For that reason, they are considered matured and ready for proper slaughter and sacrifice.