Mantra 9

न सन्दृशे तिष्ठति रूपमस्य न चक्षुषा पश्यति कश्चनैनम् ।हृदा मनीषा मनसाभिक्लृप्तो य एतद्विदुरमृतास्ते भवन्ति ॥ ९ ॥

In plain words

His form does not stand within the range of sight; no one sees him with the eye. He is made evident by the heart, by discerning intelligence, by reflection [of the mind]: those who know this become immortal.