For Mumbaikars trains are an essential means of transport.
As Alan Johnson, a former home secretary, pointed out, biometrics were an essential means of identification.
Vision screening is an essential means of identifying children at risk of developing amblyopia.
"Successive governments, committed to increasing mobility, have regarded educational policy as the essential means to this end," Goldthorpe observes.
The power to pardon is an essential means of justice, allowing a governor to right what the law got wrong.
In one response, he said: "The political centre has lost its power to persuade and its essential means of connection to the people it seeks to represent.
Instead of investing in upgrading this essential means of public transport, the governor, a civil engineer, wants to widen the street for cars.
Making matters worse, the Taliban have issued a new decree threatening death to any relief worker caught using a satellite telephone, an essential means of communication.
Cellphones are widely considered essential means of self-expression, he pointed out, but the phones are so cheap that employees can afford to buy their own.
"The threat advisory system, I believe, is an essential means of communication to the citizens," Mr. Ridge said, adding that "it means that the intelligence community says at this particular period of time, we think the threat's been increased".
The idea — of painting limited to its essential means — was powerfully espoused by the critic Clement Greenberg, and was further refined by Michael Fried, an art historian and critic who was Stella's classmate at Princeton.
