Books are the ladder of human progress. Similar quotes include:

1. Books are tools for cultivating the soul. ——Hugo.

2. Books are the nutrition of the world. ——Shakespeare.

3. Books are tools for cultivating wisdom. ——Kwameshaus.

4. The entire past soul lies in the book. ——Carlisle.

5. Books are the rich blood of a great mind. ——Milton.

6. Books are the summary of human knowledge. ——Shakespeare.

7. Books are the ladder of human progress. ——Gorky.