By degrees. Little by little means in small steps. Maybe a fun way to think about it is "elephant bites" How would you eat a whole elephant!? All at once? Or "little by little" ?

I find the song on the internet. I like it. It impressed me. Thank you.

When i saw your question, immediately i remembered this song from Oasis, maybe can help you to understand how this expression can fits in some cases 'Cause little by little We gave you everything you ever dreamed of Little by little The wheels of your life have slowly fallen off Little by little You have to give it all in all your life And all the time I just asked myself why, are you really here?