Class One. Maamar Hayom Haras Olom 5713 part one. Maase is the end of lifnei haTzimtzum and Machshava means Atzilus. All year only Sof Maase [Kav] comes into Atzilus, on Rosh Hashana Techilas Maasecha [Ohr Lifnei HaTzimtzum that is the mekor for Olomos and higher] also comes down until Asiya. Machshava is Atzilus [explanation: Koach HaGiluy and not a Livush].
Class Two. Rosh Hashana we reach Techillas Maasecha (and higher). This manifests in the idea of Is’hapcha that is higher than Is’kafia. The Rebbe explains two levels in Is’hapcha: A. Where the darkness is replaced by light, B. Where the darkness itself shines. This latter idea is the true uniqueness of Rosh Hashana.
