Valli's deepest desire was to enjoy a ride on the bus. The words and phrases that tell us this are:

(i) A fascinating thing

(ii) the sight of the bus

(iii) a source of unending joy

(iv) a tiny wish crept into her head

(v) she watched the bus

(vi) wanted to ride on that bus

(vii) became stronger and stronger

(vii) picked up small details about the bus journey.