NUM195 … Endeavour to shut your eyes and [limit] your sense of sight, so that you do not look at what you do not need [to see] or at what would distract you from reflecting on what would benefit you. Abstain from looking that is superfluous, as you abstain from something that would harm you. The Creator cautioned us in this regard: “Do not stray after your heart and eyes” (Bemidbar 15:39); and our Masters, of blessed memory, said: “The heart and the eye are the two agents of sin” (Yerushalmi, Berachos 1:5). Instead, use your [sense of] sight, your vision, to behold the creations of the Creator, May He be exalted, to examine them and reflect upon them, and apprehend through them the Creator’s power, wisdom, and goodness, as David, peace be upon him, said: “When I see Your heavens, the work of Your fingers...” (Tehillim 8:4); “The heavens tell of the glory of God...” (ibid. 19:2), and the rest of the psalm.