The lituus was a wooden staff, short enough to be carried in one hand, curved into a hook at its upper end, and it was the defining tool of the Roman augur, the priestly official responsible for reading the will of the gods primarily through the observation of birds. Standing at a fixed point, the augur used the lituus to mark out a templum in the sky and on the ground, a formally bounded space within which any observed sign, the direction, number and species of birds in flight, their calls, the way sacred chickens fed, counted as valid and outside of which the same events carried no religious significance at all. This act of ritually defining space before interpreting it inside that space is one of the clearest examples in Roman religion of how precisely bounded correct religious procedure had to be for its results to count as legitimate.
Roman public life built the augur's findings, the auspicia, directly into its decision making machinery. Before convening the Senate, holding an election, or marching an army out to battle, a magistrate was required to take the auspices, and an unfavourable reading could halt or postpone the action regardless of the magistrate's own wishes, a check political actors sometimes manipulated but could rarely ignore outright without provoking genuine religious and political controversy. The lituus, as the augur's visible instrument, accordingly became one of the most immediately recognisable emblems of Roman religious authority, appearing on coins, funerary monuments and public art as shorthand for the augural office itself.