What exactly is the difference between a mizbei'ach and a matzeiva, and why did the status of matzeivot change so drastically? We look at the opinions of Rambam and Rabbi Samson Raphael Hirsch.
Parashat Vayishlach tells of Yaakov's return to Eretz Canaan. Upon his return, he revisits the city he named Bet-El, where God appeared to him when he had initially fled Canaan over twenty years earlier. There in Bet-El, Yaakov erects a mizbei'ach – an altar (35:7), as well as a matzeiva – a monument (35:14). Much later in Chumash (Devarim 16:22), the Torah strictly forbids erecting a matzeiva, calling it "despised" by God. The Sifrei there notes that a matzeiva is "ahuva la-avot, senu'a la-banim" – "beloved for the fathers, despised for the children." Meaning, erecting these monuments to God was an admirable practice during the time of the patriarchs, something "beloved" by the Almighty, whereas for future generations it is strictly forbidden and "despised."
What exactly is the difference between a mizbei'ach and a matzeiva, and why did the status of matzeivot change so drastically?
The Ramban, in his commentary to Parashat Vayetze (28:18), points to two differences between a mizbei'ach and a matzeiva, one structural, the other procedural. A mizbei'ach, as we know from other sources, as well, is made from many stones, whereas a matzeiva is a single stone. Secondly, the Ramban writes, matzeivot were used specifically for "nesakhim" – libations. Twice Yaakov erects a matzeiva in Bet-El, once during his departure from Canaan, and once after his return, and in both instances he pours oil over it (28:18, 35:14; in the second instances, it appears that he poured wine, as well). A mizbei'ach, by contrast, is used for animal and meal offerings, as well. The Ramban speculates that the Canaanites had institutionalized the use of matzeivot as part of their pagan worship to a greater extent than they did altars. For this reason, then, the Torah strictly forbade the use of matzeivot while it sanctioned – and in fact obligated – the building and use of altars.
Rav Shimshon Refael Hirsch, loyal to his general approach of attributing symbolic significance to the laws and prohibitions of the Torah, explains the difference between a matzeiva and a mizbei'ach by unearthing the symbolic meaning of each. As mentioned, a matzeiva consists of nothing more than a single stone. The human being does nothing to this stone other than designate it for ritual use. A matzeiva, then, symbolizes the acts of God, divine power, human passivity and futility in relation to the Almighty's unlimited control. The matzeiva therefore served as a means of expressing man's gratitude to the Almighty and his attribution of all his success to Him. By contrast, the mizbei'ach, which man creates, represents human input and manipulation of the natural world. It is used for sacrifices – the symbol of man's absolute, limitless commitment and devotion to the service of God. It turns out, then, that through a matzeiva one expressed feelings of gratitude and appreciation, whereas the altar was used to express one's commitment to the active service of the Almighty.
For this reason, Rav Hirsch explains, the use of matzeivot became entirely forbidden after the giving of the Torah. Among the central messages of the Torah is that there can be no separation between passive recognition of God and the active service of God. Benei Yisrael's acceptance of the Torah meant their transformation from admirers to servants; loyalty to the Torah means that one is not only cognizant of God's power and authority, but enthusiastically willing to sacrifice of himself towards the service of God. Therefore, after Matan Torah, all offerings – including libations, the "matzeiva offerings" – must be brought specifically on a mizbei'ach, for at this point, feelings of thanksgiving and gratitude must be accompanied by sincere devotion and commitment to sacrifice.