Full Idea
The most important (ontological) relations holding among truth-makers are the part and whole relations.
Gist of Idea
Part-whole is the key relation among truth-makers
Source
Mulligan/Simons/Smith (Truth-makers [1984], §6)
Book Reference
'Truth and Truth-Making', ed/tr. Lowe,E.J./Rami,A. [Acumen 2009], p.77
A Reaction
Hence Peter Simons goes off and writes the best known book on mereology. Looks very promising to me.