superluminal said:1) Photoelectric effect, Millikan oil drop experiment, Electron microscopes, etc.
2) I do not understand this.
the point is that electrons and people's minds are phenomena that are perceivable only by their symptoms. You cannot actually "see" an electron or a persons mind, and when the question of perceiving these phenomena is raised it becomes a question of "perceivable to whom?"
It is not like everyone on the street or even everyone in the field of science has completed the necessary requirements to directly perceive the symptoms that denote the reality of an electron.
In other words if you want to say "I don't see it" your statement only becomes credible if you are capable in that field of knowledge.