When an idea, whether real or not, is of a nature to interest and possess the mind, it is said to have life, that is, to live in the mind which is the recipient of it ... [W]hen some great enunciation, whether true or false, about human nature, or present good, or government, or duty, or religion, is carried forward into the public throng and draws attention, then it is not only passively admitted in this or that form into the minds of men, but it becomes a living principle within them, leading them to an ever-new contemplation of itself, an acting upon it and a propagation of it...
It will, in proportion to its native vigour and subtelty, introduce itself into the framework and details of social life, changing public opinion and supporting or undermining the foundations of established order ...
This process is called the development of an idea ... And it has this necessary characteristic, - that, since its province is the busy scene of human life, it cannot develop at all, except either by destroying, or modifying and incorporating with itself, existing modes of thinking and acting.
Its development then is not like a mathematical theorem worked out on paper, in which each successsive advance is a pure evolution from a foregoing, but it is carried on through individuals and bodies of men; it employs their minds as instruments, and depends upon them while it uses them.
Quotation from: John Henry Newman An essay on the development of Christian doctrine[1845] London, Penguin Books, 1974 pp 97-9
