cornerstones

1. the fundamental assumptions from which something is begun or developed or calculated or explainedExamples: "the whole argument rested on a basis of conjecture"Synonyms: base, basis, cornerstone, foundation, fundament, groundwork

2. a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremoniesSynonyms: cornerstone

3. a stone at the outer corner of two intersecting masonry wallsSynonyms: cornerstone