Which light is sweet?
Rashi: The light of Torah.
Ibn Ezra: Because the senses join in the brain] above the forehead, it uses a word appropriate for a different sense. This is like "Re'eh Rei'ach Bni" (Bereishis 27:27), "v'Chol ha'Am Ro'im Es ha'Kolos" (Shemos 20:12). This is connected to the previous verse; one should always engage in doing good, and not engage in another Simchah.
Rashbam: Light of the sun is sweet and good for the eyes.
Rid: The air of this world is called Ohr. This world is very sweet for the creations; one does not want to leave the world. The prefix Vov in u'Masok is superfluous, like "v'Ayah va'Anah" (Bereishis 36:24).
Seforno: Having proper children is an important matter. The eternal light attained in Tzelem Elokim in them is sweet and excellent.
Metzudas David: This is a metaphor; light is not edible, that it can be sweet. Man's life is good; he benefits from daylight.
Is it good for eyes to see the sun? This damages the eyes!
Rashi (from Shocher Tov 49:1): Happy are eyes that see a Halachah that was clarified.
Seforno: In the eyes of this Tzelem [Elokim], an intellect in potential, it is good to see the sun and live the merit of life, for in it he actualizes acquiring eternal perfection - one Sha'ah of Torah and good deeds in this world is better than all of the world to come (Avos 4:21).
Metzudas David: It is good that they can still see the sun (he is still alive). The matter is repeated in different words.
