यो ह वै प्रतिष्ठां वेद प्रतितिष्ठति समेप्रतितिष्ठति दुर्गे चक्षुर्वै प्रतिष्ठा चक्षुषाहि समे च दुर्गे च प्रतितिष्ठति प्रतिति-ष्ठति समे प्रतितिष्ठति दुर्गे य एवं वेद ॥
In plain words
Whoever truly knows what gives him footing stands firm on level ground, and stands firm on rough ground too. That footing is the eye — because it's the eye that keeps you steady, on smooth terrain and on treacherous terrain alike. He stands firm, stands firm on level ground, stands firm on rough ground, simply by knowing this.
Close to the Sanskrit
He who indeed knows the foothold stands firm on level ground, stands firm in difficult terrain; the eye, verily, is the foothold; for by the eye, indeed, one stands firm on level ground and in difficult terrain, stands firm — stands firm on level ground, stands firm in difficult terrain — he who knows thus.