Three years ago today, a demoralized third-place Liberal party with 35 seats elected Justin Trudeau as its leader.

The next day, Trudeau haltingly stood in the Commons to follow a hard-hitting NDP question from Tom Mulcair by asking the Prime Minister a sleepy query about tariffs impacting the middle class.

The prime minister shook his head, grinned and flicked it aside.

Trudeau did not look ready.

Just over 1,000 days later, Trudeau is a world-figure Prime Minister commanding rapture ratings in public opinion with a majority government firmly in hand. Stephen Harper has become a 'where's Waldo?' exercise in media coverage. Tom Mulcair is a dead NDP leader walking.

This illustrates the hardest and most hopeful lesson in politics.

Unpredictable change is the only consistency. What seems a certainty today is tomorrow's jaw-dropping shocker.

Liberals believing they are unbeatable for the next eight years, as both two opposition parties flail about on policy direction with no obvious prospects for resurrection under new leadership, don't know their history.

With their six-month anniversary as an elected government next week, the Liberals are already showing signs the new boss is the same as the old boss, albeit with sunglasses instead of a scowl.

Be it releasing a budget condemned for being shrouded in fiscal fog, deceptions on the Saudi arms deal or a flaccid legislative agenda which has seen only three housekeeping bills passed so far, an early report card would not be suitable for framing. This government so far excels only at photo-ops, consultations and Harper policy reversals.

It's going to be at least a year before the opposition parties get out from under their leadership limbo. The Liberal government should enjoy the moment.

Three years, as Justin Trudeau probably realized this morning when leadership convention reminders popped up on Facebook, changes everything.

At the moment when a government's invincibility seems endless, opposition opportunity begins.

That's the Last Word...