I think being a mother is the greatest responsibility in the world. Imagine carrying your baby in you for months and suffering the nausea, sleepless nights, ensuring you are on the proper diet for another being depends on you to survive, to make sure he/she comes into this world with all the limbs and mind intact.
Having to endure the most painful time during delivery, you also have to ensure the baby grows up to be healthy, educated, loving, kind ..... all these do not happen within a second. It takes a lifetime and it is said that learning is a daily affair, you learn something new everyday of your life.
We have our mothers to thank for bringing us into this world, taking care of us until we are old enough to take care of ourselves and to take care of her in return. Having met the Dharma, we learn that every being has been our mother before, so we should treat everyone as how we would treat our very own mother.