Leonardo da Vinci Quotes

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

We have to learn again that science without contact with experiments is an enterprise which is likely to go completely astray into imaginary conjecture.

The only relevant test of the validity of a hypothesis is comparison of prediction with experience.

Theorists can be wrong; only nature is always right.

Natural objects, for example, must be experienced before any theorizing about them can occur.

When we human beings hypothesize that a law of nature holds - even temporarily or situationally - we are creating an idea, but we are also making a hypothesis about how nature behaves, whose truth or usefulness has nothing to do with what we know or believe.

The strongest arguments prove nothing so long as the conclusions are not verified by experience. Experimental science is the queen of sciences and the goal of all speculation.

Avoid the precepts of those thinkers whose reasoning is not confirmed by experience.

There is a fundamental difference between religion, which is based on authority, [and] science, which is based on observation and reason. Science will win because it works.

Experience alone can decide on truth.

All good intellects have repeated, since Bacon's time, that there can be no real knowledge but which is based on observed facts.

There are two modes of acquiring knowledge, namely by reasoning and experience. Reasoning draws a conclusion and makes us grant the conclusion, but does not make the conclusion certain, nor does it remove doubt so that the mind may rest on the intuition of truth, unless the mind discovers it by the path of experience.

Experience by itself teaches nothing... Without theory, experience has no meaning. Without theory, one has no questions to ask. Hence, without theory, there is no learning.

The scientists from Franklin to Morse were clear thinkers and did not produce erroneous theories. The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane. Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.

Religion is based upon blind faith supported by no evidence. Science is based upon confidence that results from evidence - and that confidence can be modified and/or reversed by further observations and experimentation. Science approaches truth, closer and closer, by hard dedicated work. Religion already has it all decided, and it's in the book. It's dogma, unchangeable, and unaffected by reality and whatever facts we come upon in the real world.

Theory and practice sometimes clash. And when that happens, theory loses. Every single time.

In the philosophic sense, observation shows and experiment teaches.

In one word, to draw the rule from experience, one must generalize; this is a necessity that imposes itself on the most circumspect observer.

Experimental evidence is the final arbiter of right and wrong.

But there are roughly two sorts of informed people, aren't there? People who start off right by observing the pitfalls and mistakes and going round them, and the people who fall into them and get out and know they're there because of that. They both come to the same conclusions but they don't have quite the same point of view.

Science has long been in the value business. Despite a widespread belief to the contrary, scientific validity is not the result of scientists abstaining from making value judgments; rather, scientific validity is the result of scientists making their best efforts to value principles of reasoning that link their beliefs to reality, through reliable chains of evidence and argument.

Though experience be our only guide in reasoning concerning matters of fact; it must be acknowledged, that this guide is not altogether infallible, but in some cases is apt to lead us into errors.

Rationalism doesn't require "belief," only observation. The real, measurable world doesn't care what you believe.

All our knowledge hast its origins in our perceptions … In nature there is no effect without a cause … Experience never errs; it is only your judgments that err by promising themselves effects such as are not caused by your experiments … Science is the observation of things possible, whether present or past; prescience is the knowledge of things which may come to pass.

Watching something is nothing like doing it.