आलम्बनतयाभाति योऽस्मत्प्रत्ययशब्दयोः ।अन्तःकरणसंभिन्नबोधः स त्वंपदाभिधः ॥ ४४ ॥
In plain words
That which shines as the direct support of the thought and word 'I'—consciousness reflected in and blended with the mind—is what is designated by the term 'thou'.
Close to the Sanskrit
That which shines forth as the support of the notion and word 'I', being consciousness blended with the inner instrument, is designated by the term 'thou'.