Text 19]
Bhāgavatam is the Answer
571
TEXT 18
मुखतस्तालु निर्भिन्नं जिह्वा तत्रोपजायते । ततो नानारसो जज्ञे जिह्वया योऽधिगम्यते ॥१८॥
mukhatas tālu nirbhinnam   jihvā tatropajāyate   tato nānā-raso jajñe   jihvayā yo 'dhigamyate
mukhatah —from the mouth;  tālu —the palate;  nirbhinnam —being generated;  jihvā —the tongue;  tatra —thereupon;  upajāyate —becomes manifested;  tatah —thereupon;  nānā-rasah —various tastes;  jajñe —became manifested;  jihvayā —by the tongue;  yah —which;  adhigamyate —become relished.
TRANSLATION
From the mouth the palate became manifested, and thereupon the tongue was also generated. After this all the different tastes came into existence so that the tongue can relish them.
PURPORT
This gradual process of evolution suggests the explanation of the controlling deities ( adhidaiva ) because Varuṇa is the controlling deity for all relishable juices. Therefore the mouth becomes the resting place for the tongue, which tastes all the different juices of which the controlling deity is the Varuṇa. It suggests, therefore, that Varuṇa was also generated along with the development of the tongue. The tongue and the palate, being instrumental, are  adhibhūtam , or the forms of matter, but the functioning deity who is a living entity is  adhidaiva , whereas the person undergoing the function is  adhyātmic , and thus the three categories are also explained as to their birth after the opening of the mouth of the  virāṭa puruṣa . The four principles mentioned here in this verse serve to explain the three main principles, namely the  adhyātma ,  adhidaiva  and  adhibhūtam , as explained before.
TEXT 19
विवक्षोर्मुखतो भूमो वह्निर्वाग् व्याहृतं तयोः । जले चै तस्य सुचिरं निरोधः समजायत ॥१९॥