The ship that carried that mythical hero to triumph over the minotaur, and to Antiope, took its lumps in the roughening waters of the Aegean Sea. Each time it returned, on the dock the old repairman carried the splintered boards of the wooden hulk and laid them in his shed. After a time, all of the ship's original boards were heaped in the shed, waterlogged, and the ship that ferried Theseus over the sea was made solely of repair parts.
Surely the ship on which Theseus continued to sail was the fabled ship of Theseus. But what if the old repairman at the dock should construct of the old parts kept in the shed the former ship? Which then would be the true ship of Theseus?
The problem is one of identity.
It concerns the relationship between the physical ship and the conceptual. Precisely, the problem is that a thing can retain its conceptual identity without the physical. The ship kept up the appearance of the first, so that even though its parts were new, the ship conceptually was not.
Appearance is not determinative - St. Peter's was St. Peter's from Michelangelo to Bernini - but it raises an interesting question: Are not we humans mere ships, preserving with spare parts the outer hull of our physicality? And is not our identity, whose basis is the physical, purely conceptual?
When you judge another person, the assessment is both physical and not. The look of a person, the tone of one's voice match not the power of the words made of the tones and the look. The words and the sense beyond make in the mind the concept. The concept, its name a sound made from the mouth, takes on properties in the mind apart from the physical sound.
To say a person has a good heart or a good soul is to mean the person is a good concept. The concept finds its base in reality, in the physical. The good heart and the good soul after all, are functions of the physical actions of a person. A person may speak, may carry your sack for you or merely look a certain way, to craft in your mind a good heart or good soul.
The trouble is often what people represent for others is less than true.
People stow from others the things that make them unique, creating for the outer world a straw man or woman with a name, with an identity of its own that becomes a concept, until one person is two concepts - one of the self, and one of the self in the eyes of others.