My lovely bride will accuse me of getting lost in the details, but I will counter that I'm just seeking a better understanding of God's revelation to us.
In the 19th chapter of the Book of Exodus (featured in the Office of Readings for Friday of the Second Week of Lent), God announced to Moses that he was going to appear in a dense cloud before Israel. In the New American Bible (NAB) translation used by the Catholic Church in her liturgies, God instructs Moses, "Go to the people and have them sanctify themselves today and tomorrow." (Exodus 19:10, NAB) A few verses later, "Moses came down from the mountain to the people and had them sanctify themselves and wash their garments." (Exodus 19:14, NAB)
I was a little confused about the meaning of the verb "sanctify" and how the Israelites would do it to themselves, so I looked up the passage in my Revised Standard Version (RSV). The translation is different, and it seems to me that the meaning changes. "Go to the people and consecrate them today and tomorrow" (Exodus 19:10, NAB) and "Moses went down from the mountain to the people, and consecrated the people; and they washed their garments." (Exodus 19:14, RSV)
In the NAB, the people sanctify themselves. In the RSV, Moses consecrates the people. Sanctify means to make holy, or dedicated to the service of God. Consecrate means much the same thing, although I've always thought that there was a subtle difference, based on the second or third definitions of holy. My confusion remains, however, between whether the Israelites did it to themselves or had it done to them by Moses.