When the roof becomes unreachable.

Picture the villages of Kent and Essex in the spring of 1381. The Black Death killed nearly a third of the population thirty years earlier. Land has become scarce. Lords raise rents and labour dues brutally.

An average peasant must now hand over half or more of his harvest just to stay on the land his family has worked for generations. You smell the wet earth, you hear the plows fall silent.

Families crowd into tiny, cold, smoky cottages. Children go hungry. Parents watch the lords' estates expand while they are evicted or crushed by debt.

A poll tax — a flat tax per head — has just been imposed for the third time in four years. It is the last straw.

Within weeks, thousands of peasants rise up. They march on London, armed with scythes and staves. They burn the tax rolls, open the prisons, execute the tax collectors. On 15 June 1381, the young 14-year-old King Richard II must meet them in person at Smithfield.

Paris, 1788. A craftsman climbs the narrow, dark stairwell of his building. Rents and the price of bread weigh ever more heavily on working-class households.

Wealthy aristocrats and financiers own entire buildings they rent out dearly. Families crowd into tiny, damp, unsanitary rooms. You smell the mould and soot. You hear the quarrels in the courtyard, children crying from hunger.

The common people watch the nobles' mansions expand while they are shut out. The burden of housing becomes a slow poison. Elites grow rich on land rent while the people are pushed out.

The dam breaks in 1789. The Bastille falls on 14 July. The French Revolution erupts.

Winter 1916. Picture the frozen villages of the Tsarist Empire. Peasants, hunched, head home after a day of work on fields that no longer truly belong to them. The vast estates of the nobles and the Church stretch as far as the eye can see.

An average peasant must give up a large share of his meagre harvest just to stay on the land his family has worked for generations. Meanwhile, in St. Petersburg and Moscow, factory workers live in squalid barracks, paying exorbitant rents for rooms shared among many.

The Tsar and the great landowners grow rich. Small peasants and workers are shut out of land and housing. Anger builds silently for years.

Then, in February 1917, the dam breaks. The women of Petrograd take to the streets demanding bread. Within days, revolution erupts. The Tsar abdicates. In October, the Bolsheviks seize power with their simple, powerful slogan: "Peace, bread, land!"