The statement 'cannot be confined ' is important to the central idea .
Explanation: The statement cannot be confined only makes sure that the New York and Brooklyn bridges had more advantages than one
* The height, span and the cost of the bridge was something unheard of .
* To a city whose population was around 6 lakh , the bridge offered to open new avenues in trade and commerce
* This apart the bridge was a total visual delight .
* science and courage together made it possible.