A pair of statements may be taken conjunctively or disjunctively; for example, "It lightens and it thunders ," is conjunctive, "It lightens or it thunders" is disjunctive. Each such individual act of connecting a pair of statements is a new monad for the mathematician .
Charles Sanders Peirce (1982). “Writings of Charles S. Peirce: 1857-1866”, p.268, Indiana University Press