In the political philosophy of Thomas Hobbes, the state of nature is a hypothetical social condition in which men found themselves prior to the establishment of government and its institutions. He uses this hypothetical scenario to justify the existence of his recommended political system.
In the state of nature, the law of the jungle prevails. In this perpetual state of “all against all,” everyone is at each other's throats. In the absence of government, law courts, or enforcement agencies, people can do pretty much what they like consistent with their physical strength.
In such a savage environment, none of the features of modern civilization are possible, be it learning, trade, or scientific discovery. This is because no one can be safe and secure. As social life is riven by chaos, disorder, and a complete lack of security, people are naturally more concerned with the fight for survival than with arts, commerce, and science.
At some point, the members of this primitive society, possessed as they are of roughly equal stocks of reason, decide that things cannot go on like this. So they come together and invest absolute power in a sovereign ruler, who will use that power to keep the peace and maintain good order. In effect, the sovereign remains in the state of nature in that he can pretty well do as he pleases. But for Hobbes, this is a small price to pay to ensure that society remains free from anarchy and chronic disorder.