The writer has three sources: imagination, observation…

Reason, observation, and experience; the holy trinity of science.

— Robert Green Ingersoll

A writer needs three things, experience, observation, and imagination, any two of which, at times any one of which, can supply the lack of…

— William Faulkner

I am fond of history and am very well contented to take the false with the true. In the principal facts they have sources…

— Jane Austen

I think that for thousands of years people have made the observation that there are certain kinds of extreme depressive states that seem to…

— Kay Redfield Jamison

Science has to be understood in its broadest sense, as a method for apprehending all observable reality, and not merely as an instrument for…

— Alexis Carrel

The observation of the way in which the children pass from the first disordered movements to those which are spontaneous and ordered -- this…

— Maria Montessori

There are few defects in our nature so glaring as not to be veiled from observation by politeness and good-breeding.

— Stanisław I Leszczyński

“The person who can learn by observation can create his own culture.”

— Santosh Kalwar

But what is of great importance to me is observation of the movement of colors.

— Robert Delaunay

No theory about our bodies as mere objects of observation and calculation (as distinct from partners in communicative interaction, assumed to be free) can…

— Allen W. Wood

We know nothing of the principle of health, the positive of which pathology is the negative, except from observation and experience. And nothing but…

— Florence Nightingale

Biochemists and biologists who adhere blindly to the Darwinism theory search for results that will be in agreement with their theories and consequently orient…

— Pierre-Paul Grasse

Observation and theory get on best when they are mixed together, both helping one another in the pursuit of truth. It is a good…

— Arthur Eddington

We ought to observe that practice which is the hardest of all-especially for young physicians-we ought to throw in no medicine at all-to abstain-to…

— John Randolph of Roanoke

The young man [Turgot] destined for an ecclesiastical career was placed within walls carefully designed to keep out all currents of new thought; his…

— Andrew Dickson White