We normally use a calendar to look ahead and plan what's coming. But God's people used a calendar to remind them of what he has done. We too need to look back and remember, because often we don't really know what's ahead. Whatever does come, we'll be more ready for it if we have been remember-ing what God has done.
Psalm 95 is probably a psalm from Israel's calendar. It calls them to rejoice in who God is and what he has done, to help them not fear what lies ahead. It's a psalm that invites us to rejoice in faith and soften our hearts. Come, this Sunday, "let us sing unto the Lord!"