"When he sees the luxurious residence or the charming country house of a wealthy person, a poor workingman often asks himself: 'Why is there such inequality in the world?'
"How many volumes have been written about equality among men! How much blood has been spilled for this idea! And yet, in spite of all, we still have the rich and the poor …
"Let us imagine that one day all the inhabitants of the world would assemble to put into effect this sharing of all goods; and that in fact each person, granted that the world is very big, received an exactly equal portion of the wealth existing on earth.
"Then what? That very evening one man might say, 'Today I worked hard: now I am going to take rest.' Another might state, 'I understand this sharing of goods well; so let’s drink and celebrate such an extraordinary happening.' On the other hand, another might say, 'Now I am going to set to work with a will so as to reap the greatest benefit I can from what I have received.' And so, starting on the next day, the first man would have only the amount given him; the second would have less, and the third would have increased his.
"Then what do we do? Start redistributing the wealth all over again?
"Even if everybody began to work right away with all his might and at the same time, the results would not be identical at all. There are, in fact, different kinds of work which are unequally productive; nor do all workers enjoy the same identical capacities. This leads to a diversity of results achieved, and consequently to differences in people’s profits.
"What would have to be imposed so that, once the division of goods was accomplished, people could continue to live on a basis of equality understood in this sense? All workers would have to perform the same tasks, all possess equal intelligence and ability, have similar professional training, the same degree of health and strength, and especially the same ability and desire to put forth the necessary efforts. All of this is quite utopian.
"To continue the argument, even if there were only two persons in the world, they would not succeed in maintaining absolute equality; for in the whole universe there are no two things completely identical in every respect …
"In spite of this, the human mind still desires to bring about certain equality among men. Is there any possibility that this can happen? Yes, no doubt. Every man, whoever he is, whatever he possesses and whatever he is capable of doing, owes all this to God the Creator of the universe. Of himself man is nothing. From this point of view all of us are absolutely equal.
"Furthermore we all possess free will, which makes us masters of all our actions. This too constitutes the basic equality of all men on earth. But the use made of our free will is not the same in all cases; it depends in fact on each man’s own determination, on the extent to which he makes use of this precious gift; for not all do so to the same degree. It follows that not even after death will perfect equality be achieved; it will not in fact exist, because every man will receive a just reward or punishment according to his deeds, good or evil."
— St. Maximilian Kolbe, from The Kolbe Reader (highly recommended)
Thanks to reader Mary for the tip.