warp and woof

noun2

1. •
   The threads in a woven fabric, composed of the warp (threads running lengthwise) and woof (threads running crosswise) to create the texture of the fabric.
2. •
   (figurative) The fundamental structure of any process or system.

   • … the “manifest destiny” theory that justifies the stealing of all territory contiguous to our own, and kindred topics, constitute the warp and woof of conversation. — 1857