Aristotle’s Politics, Book III, Chapter 8 The real difference between democracy and oligarchy is between poverty and wealth. Wherever the rulers, whether they be a minority or a majority, owe their power to wealth, that is an oligarchy. Wherever the poor rule, that is a democracy. Usually, where the rulers hold power by wealth, they are few, but where the poor rule, they are many, because few men are rich but all are free [if they are citizens in a city-state], and wealth and freedom are the grounds on which the two groups lay claim to government. Democracy is not necessarily only wherever the multitude has authority. Oligarchy is not necessarily wherever a minority has power over the system of government. If the majority of a citystate were wealthy and had authority, nobody would call it a democracy, just as if a small group of poor men had control over a larger rich population, nobody would call it an oligarchy. Rather, democracy is when every free citizen has authority and oligarchy is when the rich have it. Democracy is when there is a majority of free, poor men who have authority to rule, while oligarchy is when it is in the hands of the wealthy and well-born, who are a minority.

Democracy means government by the uneducated, while aristocracy means government by the badly educated.

He who is a citizen in a democracy will often not be a citizen in an oligarchy.

The difference between a democracy and a dictatorship is that in a democracy you vote first and take orders later; in a dictatorship you don't have to waste your time voting

Whether democracy or aristocracy is the better form of government constitutes a very difficult question. But, clearly, democracy inconveniences one person while aristocracy oppresses another. That is a truth which establishes itself and precludes any discussion: you are rich and I am poor.

Democracy is essentially a means, a utilitarian device for safeguarding internal peace and individual freedom. As such it is by no means infallible or certain. Nor must we forget that there has often been much more cultural and spiritual freedom under an autocratic rule than under some democracies and it is at least conceivable that under the government of a very homogeneous and doctrinaire majority democratic government might be as oppressive as the worst dictatorship.

It is accepted as democratic when public offices are allocated by lot; and as oligarchic when they are filled by election. — Aristotle, Politics, Book IV

Then an unjust democracy must be worse than an unjust oligarchy, mustn’t it?

Democracy is, among other things, the ability to say 'no' to the boss. But a man cannot say 'no' to the boss, unless he is sure of being able to eat when the boss's favour has been withdrawn.

The nation, so long a victim of monarchical selfishness, thought to deliver itself for ever by declaring that it alone was sovereign. But what was monarchy? The sovereignty of one man. What is democracy? The sovereignty of the nation, or, rather, of the national majority. But it is, in both cases, the sovereignty of man instead of the sovereignty of the law, the sovereignty of the will instead of the sovereignty of the reason; in one word, the passions instead of justice. Undoubtedly, when a nation passes from the monarchical to the democratic state, there is progress, because in multiplying the sovereigns we increase the opportunities of the reason to substitute itself for the will; but in reality there is no revolution in the government, since the principle remains the same. Now, we have the proof to-day that, with the most perfect democracy, we cannot be free.

Democracy extends the sphere of individual freedom, socialism restricts it. Democracy attaches all possible value to each man; socialism makes each man a mere agent, a mere number. Democracy and socialism have nothing in common but one word: equality. But notice the difference: while democracy seeks equality in liberty, socialism seeks equality in restraint and servitude.

Democracy is based on Abraham Lincoln's principal than you 'can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time. If a government is corrupt and fails to improve people's lives, enough citizens will eventually realise this and replace the government. But government control of the media undermines Lincoln's logic, because it prevents citizens from realising the truth. Trough its monopoly over the media, the ruling oligarchy can repeatedly blame all its failures on others, and divert attention to external threats - either real or imaginary.
When you live under such an oligarchy, there is always some crisis or other that takes priority over boring stuff such as healthcare and pollution. If the nation is facing external invasion or diabolical subversion, who has time to worry about overcrowded hospitals and polluted rivers? By manufacturing a never-ending stream of crises, a corrupt oligarchy can prolong its rule indefinitely.

Democracy does not merely mean periodic elections. It means a government held accountable to the people between elections.

Democracy is the theory that the common people know what they want and deserve to get it good and hard.