Isaiah Berlin, Four Essays on Liberty

The simple point which I am concerned to make is that where ultimate values are irreconcilable, clear-cut solutions cannot, in principle, be found. To decide rationally in such situations is to decide in the light of general ideals, the overall pattern of life pursued by a man or a group or a society.
Introduction to ‘Four Essays on Liberty’ (1969) 42 [l] 

The need to choose, to sacrifice some ultimate values to others, turns out to be a permanent characteristic of the human predicament. ibid. 43 [li] 

Those, no doubt, are in some way fortunate who have brought themselves, or have been brought by others, to obey some ultimate principle before the bar of which all problems can be brought. Single-minded monists, ruthless fanatics, men possessed by an all-embracing coherent vision do not know the doubts and agonies of those who cannot wholly blind themselves to reality.
ibid. 47 [lv] 

The notion that there must exist final objective answers to normative questions, truths that can be demonstrated or directly intuited, that it is in principle possible to discover a harmonious pattern in which all values are reconciled, and that it is towards this unique goal that we must make; that we can uncover some single central principle that shapes this vision, a principle which, once found, will govern our lives – this ancient and almost universal belief, on which so much traditional thought and action and philosophical doctrine rests, seems to me invalid, and at times to have led (and still to lead) to absurdities in theory and barbarous consequences in practice.
ibid. 47–8 [lv–lvi] 

The fundamental sense of freedom is freedom from chains, from imprisonment, from enslavement by others. The rest is extension of this sense, or else metaphor.
ibid. 48 [lvi]

T]hose who have ever valued liberty for its own sake believed that to be free to choose, and not to be chosen for, is an inalienable ingredient in what makes human beings human.
ibid. 52 [lx]

Injustice, poverty, slavery, ignorance – these may be cured by reform or revolution. But men do not live only by fighting evils. They live by positive goals, individual and collective, a vast variety of them, seldom predictable, at times incompatible.
‘Political Ideas in the Twentieth Century’ (1950), L 93 [FEL 40]

Everything is what it is: liberty is liberty, not equality or fairness or justice or culture, or human happiness or a quiet conscience.
‘Two Concepts of Liberty’ (1958), L 172 [FEL 125]

It may be that the ideal of freedom to choose ends without claiming eternal validity for them, and the pluralism of values connected with this, is only the late fruit of our declining capitalist civilisation: an ideal which remote ages and primitive societies have not recognised, and one which posterity will regard with curiosity, even sympathy, but little comprehension. This may be so; but no sceptical conclusions seem to me to follow. Principles are not less sacred because their duration cannot be guaranteed. Indeed, the very desire for guarantees that our values are eternal and secure in some objective heaven is perhaps only a craving for the certainties of childhood or the absolute values of our primitive past. ‘To realise the relative validity of one’s convictions’, said an admirable writer of our time, ‘and yet stand for them unflinchingly is what distinguishes a civilised man from a barbarian.’ To demand more than this is perhaps a deep and incurable metaphysical need; but to allow such a need to determine one’s practice is a symptom of an equally deep, and more dangerous, moral and political immaturity.
ibid., L 217 [FEL 172] 

Source: The Isaiah Berlin Virtual Library: http://berlin.wolf.ox.ac.uk