There are three principal means of acquiring knowledge... observation of nature, reflection, and experimentation. Observation collects facts; reflection combines them; experimentation verifies the result of that combination. Denis Diderot
The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
A battle lost or won is easily described, understood, and appreciated, but the moral growth of a great nation requires reflection, as well as observation, to appreciate it. Frederick Douglass
For this reason, the expansion of relations with all countries is on the agenda of the Islamic Republic of Iran. I mean balanced relationships, based on mutual respect and observation of each other's rights. Mahmoud Ahmadinejad
A careful analysis of the process of observation in atomic physics has shown that the subatomic particles have no meaning as isolated entities, but can only be understood as interconnections between the preparation of an experiment and the subsequent measurement. Erwin Schrodinger