And I find it impossible to sum up. So much life.
The middle novel details the years of prosperity--Kristin, finding herself mistress of a large noble estate in near-ruins thanks to Erlend's ineptitude, rises to the occasion in between birthing seven sons. Erlend wanders in and out, making himself a decent name as a border governor. They fight and make up, have another baby, fight and make up again.
Undset is incredibly good at showing the tangle of feelings, of desire and resentment, of missed cues and muddled responsibilities of a struggling marriage. Kristin's steadiness that gives her the ability to rise to being mistress of a noble estate--CEO, doctor, brewer, farmer, head of charity and society woman all rolled into one--goes along with a steady resentment that Erlend cannot be more like her even steadier father (though of course she never could love the steady man her father picked out). Only by tossing aside reality can she enjoy a bit of peace with Erlend, and that never happens for long once she has the heritage of her sons to worry about.
After a particularly nasty argument, Erlend has a brief revenge affair, which ends even worse than expected--it turns out he's been leading a plan which, had it gone well, would have marked him down as a hero of his country, but thanks to his idiocy the plan is discovered and he is tried for treason.
Always at their best in a crisis, Kristin and Erlend reconcile and thanks to the tireless labor of Simon, Kristin's former betrothed (and now brother-in-law), Erlend is freed, but at the cost of land and titles. The family retires to Kristin's childhood home, which is her own property.
In the final book is the fallout. The fragile reconciliation falls to pieces again. Life goes on until it doesn't any more. At the end, one son takes over the farm, the others scatter to seek their fortune or the cloister, and the widowed Kristin enters a convent.
I saw one review commenting on the centrality of motherhood to the book and that is a major theme--and as I first read the book over a decade ago, when I was still in the baby stage and now revisit it as my children are entering their teens, I feel it with her--the constant loss, the fears, the joys that are only remembered in retrospect and the pain that is better than joy--even more than the first time through.
But another theme that comes through is the journey of the soul to God--that all the things of life, the worries, the triumphs, the joys and sorrows--are not the main thing that most people think, nor distractions as people trying to be devout think, but the way through which God himself shows himself to us. On her way to the convent, Kristin gets sidetracked by a crowd of little boys: "And when the moment came that she had longed for all through her journey, when she stood below the cross on Feginsbrekka and looked down on Nidaros, it came not so that she could collect her thoughts for prayer or meditation. All the bells of the town burst forth at that moment to ring to Vespers, and the boys all talked together, wanting to point out all that was before her--"
Or, to put my favorite song with my favorite book,
"Every heart--every heart to love will come/But as a refugee."
Here is my review from 2006. I will read this book again. Maybe in 2030.