There are more books, written by Founder's direct and long time students, than Saotome's "Aikido and the Harmony of Nature". FYI.
This is what Saito Sensei said about the origins of Aikido:
"Aikido is a martial art. No matter how good one is in judo, if he or she takes a kendo sword and looses against a student, he or she is not a Budoka, but a Judoka. Even as number one in Japan in kendo, if he or she puts on a judogi and is thrown by a student, he or she is a Kendoka and not a Budoka. O'Sensei (The Founder) says, "This is not good."
Everything is a whole, an entirety. That is why in aikido, even if the principle of the sword is formative, all the movements in the body techniques, as well as in the weapons techniques, are entirely similar. That is why weapon techniques are indispensable in aikido. They are a part of it. Some people say aikido is a collection of techniques, but that is not true. How shall I put it? Each of them is contained in the whole. No matter which of the three you take out, bokken, jo, or taijutsu, alone it is not complete aikido. That is why weapons are an especially important part of aikido."
Those of us who actually train in Aikido must get our understanding of Aikido from our teachers, not from non-Aikido practicing individuals.