It is not impossible, but difficult to remember the syntax for all the symbols we use in latex documents. Even I find it painful to go through a cheat-sheet that contain the syntax for the symbols.
I came across an online tool, where you can scribble online with mouse and get the syntax for the symbol you want. I feel that the tool is quite helpful. Here is the snapshot of the tool in action…
[more info… Detexify2 – LaTeX symbol classifier]