Nothing, in truth, can ever replace a lost companion. Old comrades cannot be manufactured. There is nothing that can equal the treasure of so many shared memories, so many bad times endured together, so many quarrels, reconciliations, heartfelt impulses. Friendships like that cannot be reconstructed. If you plant an oak, you will hope in vain to sit soon under its shade.
For such is life. We grow rich as we plant through the early years, but then come the years when time undoes our work and cuts down our trees. One by one our comrades deprive us of their shade, and within our mourning we always feel now the secret grief of growing old.
If I search among my memories for those whose taste is lasting, if I write the balance sheet of the moments that truly counted, I surely find those that no fortune could have bought me. You cannot buy the friendship of a companion bound to you forever by ordeals endured together.
— Antoine de Saint-Exupéry, (Wind, Sand, and Stars)