This is how you prepare it to be whole again. You cut those two cords that so tentatively hold the front cover to the book. The leather that once supported the joint has long since dried out and broken clean along that line between spine and front board. But those two fraying cords ... it's tempting to leave them intact. You use to bend over backwards to work around them. But now you cut them clean with a stropped scalpel and start fresh. Then you lift the front free endpaper, carefully. Pay attention to how it feels and respond accordingly as you lift and it will pull it free from the binding. Save it; mark it; it'll get lost or you'll mix it up with the back endpaper if you don't pencil in a faint note. You'll need it later. Then, you do all of this again with the back cover. Remember, the new connections you make will be stronger than those two cords. You'll be brave and recognize this ... and you'll cut them.
Now, you'll put the textblock in the finishing press, though you've only just begun. And the contradictions continue. You'll cook wheat starch paste, bring it to a boil on your stove and stir attentively. You'll add three or four drops of clove oil to make it last a few days longer and to make it smell nice while you cook it. It's conditioning really; you'll associate the lovely fragrance with cooking paste instead of associating it with the drudgery of stirring it at a stove slowly and constantly for 20-30 minutes. Once cooled and congealed you'll strain it and then you'll apply this adhesive to the desiccated spine leather and let it sit. Inexplicably, the adhesive will release everything. You'll use a dull knife and scrape the old leather away; you'll scrape the spine clean. And this is the best ... the absolute best! When all you have is the book, the folded and sewn gatherings staring up at you, a little yellowed from the remnants of early adhesive still lingering in the crevices. You can start fresh from here, particularly if the craftsmanship was good 200 years ago. It's the absolute best thing in the world! A new canvas, cut free from the past, in the present and prepared for the future.
Any day now, you'll receive a letter from the court letting you know that you are no longer married ... and you'll be brave....