Lysander Spooner (1808-1887) defined liberty rather well. He was a libertarian but he did not deny that we have the moral duty to help others and explained how this should work. Further, he explained that the present system of land ownership is a way to oppress people. He is usually categorized as an individual anarchist. These are some little pieces from what he wrote.
From: Natural Law or The Science of Justice
(On The Right to do things your own way):
The science of justice is the science of all human rights. … It is the science of peace, and the only science of peace; since it is the science which alone can tell us on what conditions man can live in peace … with each other.
These conditions are simply these:
1st: that each man shall do, towards every other, all that justice requires him to do; as, for example, that he shall pay his debts, that he shall return borrowed or stolen property to its owner and that he shall make reparation to any injury that he may have done to the person or the property of another.
2nd: that each man shall abstain from doing to another anything that justice forbids him to do; as, for example, that he shall abstain from committing theft, robbery, arson, murder or any other crime.
So long as these conditions are fulfilled, men are at peace.
Men, no doubt, owes many other moral duties to his fellow men; such as to feed the hungry, clothe the naked, shelter the homeless, care for the sick, protect the defenceless, assist the weak, and enlighten the ignorant.
Although it is the right of anybody …. to repel injustice and compel justice, for themselves and for all who may be wronged, yet to avoid the errors that are liable to result from haste and passion… it is evidently desirable that man should associate, so far as they freely and voluntarily can do so.
Yet such associations can be rightful and desirable only in so far as the are purely voluntary. No man can be rightfully be coerced into joining one.
An association for mutual protection against injustice is like an association for mutual protection against fire of shipwreck. And there is no more right … in compelling to join or support one … against his will.
If he chooses to depend, for the protection of his own rights, solely upon himself, and upon such voluntary assistance as other persons may freely offer to him … he has the perfect right to do so. And this course would be a reasonably safe one for him to follow, so long as he himself should manifest the ordinary readiness of mankind … to go to the assistance and the defence of injured persons. … For such a man is reasonably sure of always giving friends and defenders enough in case of need, whether he shall have joined any association, or not.
Children learn the fundamental principle of natural law at a very early age. Thus they very early understand that one child must not, without a just cause, strike or otherwise hurt another; that one child must not assume any arbitrary control or domination over another… that if one child commits any of these wrongs against another, it is not only the right of the injured child to resist … but that it is also the right, and the moral duty of all other children to assist the injured party in defending his rights.
These are the fundamental principles of natural law.
(On Earth ownership):
In process of time, the robber, or slaveholding class- who had seized all the lands … began to discover that the easiest mode of managing their slaves …was to give them the responsibility of their own subsistence, and yet compel them to sell their labour to the landholding class – their former owners.
Of course, the liberated slaves …, having no lands, or other property, and no means of obtaining an independent subsistence had no alternative … but to sell their labour to the landholders in exchange only for the coarsest necessaries of life.
The whole purpose of this legislation is simply to keep one class of men in subordination and servitude to another.
What, then, is legislation? … It is, in short, the assumption of a right to banish the principle of human rights, the principle of justice itself, from off the earth, and set up their own personal will, pleasure and interests in their place.
Want to read more of his work? I can recommend this book: https://www.abebooks.com/9781729017340/Lysander-Spooner-Selected-Works-Libertarian-1729017347/plp