Today is Kṛṣṇāṣṭamī of Bhādrapadā month, for the majority this day is known as Kṛṣṇa–janmāṣṭami. But, for the śakta–upāsakas this date is also known as Kālī-jayantī. Many people have probably heard that Muṇḍamālā Tantra, Guhyātiguhya Tantra, Toḍala Tantra identify ten Viṣṇu-avatāras with ten Mahāvidyās, and according to these texts Kṛṣṇa is the manifestation of Kālī. However, the very ideas about the unity of Kṛṣṇa and Mahākāla (whose Śakti is Kālī) are also found in earlier sources, in Bhagavadgītā (11.32) Kṛṣṇa says:
कालोऽस्मि लोकक्षयकृत् | kālo’smi lokakṣayakṛt |
I am the time destroying the worlds.
If you look at the paddhatis where the Kālī-pūjā is described, then in many of them you can find borrowing from Puruṣa Suktam, for example, in the nyāsa practice or in other elements of the pūjā. This is not accidental, because the image of puruṣa symbolises Mahākāla and His Śakti – Kālī. Mahākāla Dakṣiṇāmūrti is the Śaktimān of Dakṣiṇā Kālī. Mahākāla is the Great Time, who absorbs the very time, He is the symbol of transformation that also indicates the inner yogic process. Many interesting images pointing, for example, to the original dark nature of Mahākāla and Mahākālī, are found in other sources. For example, in Rigveda (10.129. 03):
तम आसीत्तमसा गूढमग्रेऽप्रकेतं सलिलं सर्वमा इदं ।
तुच्छ्येनाभ्वपिहितं यदासीत्तपसस्तन्महिना जायतैकं ॥३॥
tama āsīttamasā gūḍhamagre’praketaṃ salilaṃ sarvamā idaṃ ।
tucchyenābhvapihitaṃ yadāsīttapasastanmahinā jāyataikaṃ ॥3॥
Initially, there was a darkness immersed in a dark abyss, all this were endless waters. That incomprehensible and unified manifested himself through the power of his heat.
A similar description is also found in Dharmaśāstra, for example in Manusmṛti (1.5):
आसीदिदं तमोभूतमप्रज्ञातमलक्षणम् ।
अप्रतर्क्यमविज्ञेयं प्रसुप्तमिव सर्वतः ॥ ५ ॥
āsīdidaṃ tamobhūtamaprajñātamalakṣaṇam |
apratarkyamavijñeyaṃ prasuptamiva sarvataḥ || 5 ||
This world was darkness, immersed in a deep sleep, incomprehensible to the mind, inseparable, unknowable.
However, the darkness associated with Mahākāla, Kālī, Kṛṣṇa and other Gods and Goddesses has no negative context. It rather as the highest reality from which the creation, maintenance and destruction of the entire universe occurs. It is also known that ṛṣi of the Puruṣa Suktam hymns is Nārāyaṇa, who is identified with this puruṣa in other sources, in Śatapatha-brāhmaṇa for example. We can find many earlier sources pointing to the identity of Mahākāla, Nārāyaṇa (Viṣṇu or Kṛṣṇa) and also Kālī – the Śakti of Mahākāla. For many nātha-yogis, Mahākāla is none other than Śiva Adināth, because Mahākāla and his Śakti are very revered in the Nātha Sampradaya. The goddess Kālī grants liberation from time and worldly impermanence to those who have established themselves in devotion and the yoga path.