May Day
The May Queen is crowned during the May Day celebrations in London's Regent's Park in 1921 Hulton Archive/Getty

May Day, also known as International Workers' Day or International Labour Day, is a national holiday in almost 80 countries, paying respect to workers all over the world.

The day was chosen to honour the people who died during a demonstration in Chicago in 1886 when workers were striking for an eight-hour working day. A bomb was thrown at the police, leading them to fire on the protesters. Four demonstrators and seven policemen died in the violence.

To commemorate the day, IB Times UK has compiled a top ten list of powerful quotes that speak about the value and power of hard work.

1. I'm a great believer in luck, and I find the harder I work, the more I have of it. Thomas Jefferson

2. A hundred times every day I remind myself that my inner and outer life depend on the labours of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am still receiving. Albert Einstein

3. A man is not paid for having a head and hands, but for using them. Elbert Hubbard

4. Thunder is good, thunder is impressive; but it is lightning that does the work. Mark Twain

5. Before the reward there must be labour. You plant before you harvest. You sow in tears before you reap joy. Ralph Ransom

6. All labour that uplifts humanity has dignity and importance and should be undertaken with painstaking excellence. Martin Luther King Jr

7. Nobody can think straight who does not work. Idleness wraps the mind. Henry Ford

8.There is no substitute for hard work. Thomas Edison

9. God sells us all things at the price of labour. Leonardo da Vinci

10. The end of labour is to gain leisure. Aristotle