Kautilya's Arthashastra 13.1.2

13.1.2

sarvajñakhyāpanaṃ tu - gṛhaguhyapravṛttijñānena pratyādeśo mukhyānām, kaṇṭakaśodhanāpasarpāvagamena prakāśanaṃ rājadviṣṭakāriṇām, vijñāpyopāyanakhyāpanam adṛṣṭasaṃsargavidyāsaṃjñādibhiḥ, videśapravṛttijñānaṃ tad ahar eva gṛhakapotena mudrāsamyuktena //

Proclamation of his omniscience is as follows:--rejection of his chief officers when their secret, domestic and other private affairs are known; revealing the names of traitors after receiving information from spies specially employed to find out such men; pointing out the impolitic aspect of any course of action suggested to him; and pretensions to the knowledge of foreign affairs by means of his power to read omens and signs invisible to others when information about foreign affairs is just received through a domestic pigeon which has brought a sealed letter.