Knowledge expands unlike physical containers
Nahj al-Balāgha|Volume 1|Book 3|Chapter 205
٢٠٥. وَقَالَ (عليه السلام): كُلُّ وِعَاءٍ يَضِيقُ بِمَا جُعِلَ فِيهِ إِلَّا وِعَاءَ الْعِلْمِ، فَإِنَّهُ يَتَّسِعُ بِهِ.
205. Amīr al-mu’minīn, peace be upon him, said: Every container gets narrower according to what is placed in it except the container of knowledge which expands instead.