For 1994’s I Know Who Holds Tomorrow, Alison Krauss took a break from recording with Union Station and instead collaborated with the Cox Family, a gospel quintet from Cotton Valley, Louisiana. The Coxes are a perfect fit for Krauss’ singular brand of immaculate sacred music, but I Know Who Holds Tomorrow also illuminates unexpected elements of her craft. “Walk Over God’s Heaven,” “Never Will Give Up,” and “Loves Me Like a Rock” are swinging, rotund blues — and surprisingly sexy for a group of singers committed to Christian music. “Where No One Stands Alone,” “Remind Me, Dear Lord,” and “Everybody Wants To Go to Heaven” present a vision of country music that is lighter than air. Imagine Hank Williams if he wore virgin cotton instead of Nudie suits, and imbibed holy water and not whiskey. For those who crave Krauss’ voice in its most ethereal state, “Jewels” is a hymn as fragile, smooth, and carefully crafted as fine porcelain. Rather than simply collect a series of sacred songs, I Know Who Holds Tomorrow draws out in understated ways the unheard aspects of Krauss’ music.