The meaning of 'covenant' is strongly debated. 'The covenant principle of God is a bond in blood sovereignly administered' (0. Palmer Robertson). It is an alliance or agreement made between two: in God's case the covenant is unilateral, that is it is always grace. The mode of the covenant takes the form of (a) a statement of ideas made known (agreed upon), (b) the agreement sealed with and by an oath, (c) the invocation of a curse to guard the solemn statute, and (d) the agreement ratified by some external act, i.e. a ritual.