1.   The general idea behind them was that they would provide a setting for vigorous entrepreneurs, capable of generating an industrial renaissance.

2.   The idea behind radar was to send out radio waves and listen for echoes from enemy craft.

3.   The idea behind the commercials is that reading is as cool and entertaining as their favorite bands.

4.   The idea behind the Homestead Act was that a nation of small, independent farmers would make the best foundation for democracy.

5.   The idea behind the ion motor is to make use of the electrical properties of ionized atoms.

6.   The idea behind these forms is to cut out fraud.

7.   The idea behind this imposition of blanket bans was to prevent the temptation to discriminate against particular Marches.

8.   The idea behind the outing is to encourage employees to get to know each other.

9.   Not only did this seem practical, but the idea behind the design was to shelter residents from the fierce winter winds.

10.   Yes, I think this is probably the idea behind the thinking, really.