Shatapatha Brahmana 8.7.1.16

8.7.1.16

yadveva viśvajyotiṣamupadadhāti | prajā vai viśvajyotiḥ prajā hyeva viśvaṃ jyotiḥ prajananamevaitadupadadhāti

And, again, as to why he lays down a Visvagyotis:--the Visvagyotis, doubtless, means progeny, for progeny indeed is all the light:--he thus lays generative power into it (or into him, Agni and the Sacrificer).