Although such scholars speculate that the deuteronomist is a later author than the priestly source, scholars believe that much of the Deuteronomic Code was a reaction against the regulations introduced by the Priestly Code, and that here it reflects the earlier situation. In the Book of Ezekiel, which some scholars believe predates the Priestly Code, meaning that according to their view the Priestly Code must post-date the Babylonian Exile, there is no mention whatever of a tithe appointed for the Levites, and in the Deuteronomic Code, though Levites have a share of the "ma'aser sheni", their share is seemingly voluntary, and it can alternatively be given to strangers, widows, and/or paternal orphans; in the Priestly Code, however, donation of the tithe to the Levites is compulsory. Of course, if the "ma'aser sheni" tithe, also mentioned in Leviticus, were originally different from "ma'aser rishon", there is a simpler explanation for the variation.