Physical Energy is a bronze sculpture by English artist George Frederic Watts. Watts was principally a painter, but also worked on sculptures from the 1870s. Physical Energy was first cast in 1902, two years before his death, and was intended to be Watts's memorial to "unknown worth". Watts said it was a symbol of "that restless physical impulse to seek the still unachieved in the domain of material things". The original plaster maquette is at the Watts Gallery, and three large bronze casts are in London, Cape Town, and Harare. Other smaller bronze casts were also made after Watts's death.
The sculpture is based on Watts's earlier colossal bronze equestrian statue of Hugh Lupus, 1st Earl of Chester, commissioned by his namesake Hugh Lupus Grosvenor, later 1st Duke of Westminster, in 1870 and completed in 1883 and displayed at Eaton Hall, Cheshire. That work was itself based on equestrian elements of the Elgin Marbles.
Watts started work on Physical Energy in 1883. The original 3.5 ton gesso grosso model (made of plaster mixed with glue size and hemp or tow) is at the Watts Gallery at Compton near Guildford. He was assisted by George Thompson and Louis Deuchars. The sculpture depicts a classical naked man on a rearing horse, set on a rectangular wedge-shaped base. His left hand holds the reins, while he shades his eyes from the sun with the right as he looks to the left. It was originally intended to be dedicated to Muhammad, Attila, Tamerlane and Genghis Khan, thought by Watts to epitomise the raw energetic will to power.
Watts was reluctant to finalise and cast the work, and continued to modify it. Millais encouraged him to have it cast in 1886, but it was not cast in bronze until 1902.
The first full-size bronze cast of the sculpture was made at Alessandro Parlanti's foundry in Fulham in 1902. It was claimed to be the largest sculpture ever cast in bronze in Britain. Watts gave the statue to the British Government. It was originally erected at the grave of Cecil Rhodes in the Matopo Hills in Zimbabwe. It now stands at the bottom of the steps at the Rhodes Memorial on Devil's Peak above Groote Schuur near Cape Town, South Africa.