[Kiowa Warrior]

I think that if Locke had said to Jack earlier on 'this place is more than just an Island in the physical sense that brought us here' Jack would have threatened to literally smack some sense into him! Maybe back then Locke did think - he did actually know - that it wasn't just an Island in the standard sense of the word, but he played it safe by only letting Jack know some of his thoughts...he wasn't sure if Jack would receive the knowledge that it was more than an Island well. And he was right to hold back!

Or maybe Locke really did consider it more of a physical Island back then, but his beliefs and outlook and perceptions have evolved and matured, whereas Jack is stubbornly refusing to move on or acknowledge anything beyond his own comfort zone.