Tis easy to build castles in the air.

Imagining an impressive future is easy when there is no need to confront the effort or obstacles involved in achieving it.

The proverb cautions that an appealing plan is not an accomplishment. What sounds grand in the imagination may be much harder to make real.

Use it to temper an ambitious proposal that has not accounted for how it would be carried out. It draws attention to the gap between envisioning a result and doing the work needed to achieve it.