It is also possible to come to important conclusions using more or less complex reasoning, without the need to experiment. Newton, Einsten and Maxwell were three scientists who discovered laws which were transcendental for humanity, although they did not do a great deal of experiments. Starting with important principles, they were able to explain the behaviour of matter, without needing to do a great many experiments. This process is called the theoretical or deductive method.
In the following visual you can see how Newton, starting from the law of universal gravitation, deduced many other laws.