There are four broad categories of animal sacrifices: ascent-offerings, peace-offerings, sin-offerings, and guilt-offerings. Now that the Tabernacle has been erected, it is unlikely that you will sin today, since you will be too overcome with religious awe and too anxiously expecting a sign from Me that I approve of your efforts in building the Tabernacle in order to secure My forgiveness for the incident of the Golden Calf. Thus, the first types of sacrifices you will offer will most likely be voluntary (ascent-offerings, grain-offerings, and peace-offerings) rather than obligatory (sin- and guilt-offerings); the laws governing voluntary sacrifices will therefore be given first, followed by the laws regarding obligatory sacrifices. Furthermore, the laws concerning individual sacrifices (both voluntary and obligatory) will be given before the laws of communal sacrifices, inasmuch as the latter will become relevant only later, once Aaron and his sons begin officiating as priests and take over the sacrificial service.
Of the voluntary sacrifices, the first whose laws will be given is the ascent-offering, since it does effect a certain kind of atonement, as will be described presently—and to teach the priests and the people at large the laws regarding these sacrifices until later.
