Lessons from Purana

Purāna are the holy scriptures in the Hindu philosophy. They are collections of numerous stories about lives of different people or Gods. Each of them suggests one or more lessons about the life. Each mortal being is expected to keep these lessons in mind at ever juncture of his life. But if one asks what exactly is the sum total or the gist of all the lessons from Purāna, then he can be told that:

अष्टादशपुराणानां सारं व्यासेन कीर्तितम्।
परोपकार: पुण्याय पापाय परपीडनम्॥

अर्थात्
महर्षी व्यासांनी सर्वांपर्यंत पोहोचविलेल्या सर्व अठरा पुराणांचं सार केवळ दोनं तत्वात सामावलं आहे.
दुस-याला मदत करणं हे पुण्य आणि दुस-याच्या पीडेचे कारण बनणं हे पाप.

In English,

Only two sentences can sum up the eighteen Purāna by Maharshee Vyās.
To help others is the divine deed. To be the source of trouble for others is the sin.