Hi Alisha, this is a famous quote by Albert Einstein. I think that what he tried to say is that knowledge is something so fundamental that one should gain it no matter what method is used to achieve it i.e., including imagination. However, once you will have obtained this knowledge, you have to use your imagination intensively to achieve an even bigger goal. It is easy to gain knowledge but it is hard to utilize one's imagination appropriately to contribute to the future development of ideas.