1 Gita Sloka Every Day - Chapter 14 - Gunatraya Vibhaga Yoga - Sloka 6

The entire content of this mail is from Swami Adidevananda's translation of Ramanuja's  Gita  Bhashya and Swami Chidbhavananda's Bhagavad Gita, both published by Ramakrishna Mission

The characteristics of the three gunas are now explained

The Function of the Gunas 5-10

1 Gita Sloka  Every Day - Chapter 14 - Gunatraya Vibhaga Yoga - Sloka 6

Tatra sattvam nirmala tvat prakasakam anamyam I

Sukha sangena badhnati jnana sangena cha anagaha II sloka 6

तत्र सत्त्वं निर्मल त्वत् प्रकासकं अनम्याम्  I
सुख संगेन बध्नति ज्ञान संगेन च अनगः II  श्लोक 6 

Of these, sattva,  being stainless,  is luminous and unobstructive. It binds, O sinless one, by creating attachment to happiness and knowledge.

The sattva guna may be compared to an evenly made clear glass. Light passes through it unobstructed and undiminished. Things seen through that glass are as vividly visible as to a normal naked eye.The sattva is similarly transparent to the brilliance of the atman. 

The characteristic nature of sattva is that it illuminates on account of its being pure. Its purity refers to being bereft of qualities that veil the light and happiness. It hence is the cause for light and happiness. Light or illumination is the enlightenment about a thing as it is. Morbidity (Disease) does not occur in its presence.The meaning is that sattva is the cause of good health.

The sattva guna however, binds the self by attachment to happiness and knowledge. When such an attachment is born, one engages in secular and vedic means for securing them. Consequently one is born in such bodies that provide the means for realising such fruits. 

Hence sattva generates knowledge and happiness as well as attachment to it.