the blowing of trumpets represented the preaching of the gospel, by which men are called to repent of sin, and to accept the salvation of Christ, which was signified by the day of atonement. Also it invited to rejoice in God, and become strangers and pilgrims on earth, which was denoted by the feast of Tabernacles, observed in the same month.
At the beginning of the year, they were called by this sound of trumpet to shake off spiritual drowsiness, to search and try their ways, and to amend them. The day of atonement was the ninth day after this; thus they were awakened to prepare for that day, by sincere and serious repentance, that it might indeed be to them a day of atonement.
The humbling of our souls for sin, and the making our peace with God, is work that requires the whole man, and the closest application of mind. On that day God spake peace to his people, and to his saints; therefore they must lay aside all their wordly business, that they might the more clearly hear that voice of joy and gladness.