This has been a very interesting discussion, with a lot of food for though from many points of view. Thank you to everyone who has posted. I've got a lot from hearing your thoughts, and especially from going over them again this morning.
Here's something relevant I read last night, from "The Secret Teachings of Aikido" by Morihei Ueshiba (O Sensei) - which coincidentally arrived about the time this thread was getting started. I have not started to read the book yet, but in the preface Doshu Moriteru Ueshiba says:
Although the practice of Aikido has become widespread, however, misunderstandings and misinterpretations of the philosophy of the art have occurred. It is our responsibility to present the true spirit of Aikido, not just its physical aspects, in order to further, and correctly advance, the cause of Aikido in contemporary society.
I will be very happy if those who are engaged in heartfelt Aikido training make this book of the Founder's lessons their daily companion and study his words often. This was also the sincere hope of the Founder and the second Doshu Kisshomaru, who are surely please by the publication of this international edition of The Secret Teachings of Aikido."
Doshu makes no reference to any level of proficiency or number or years' training one should achieve before reading the Founder's words, or for that matter before presenting the true spirit of Aikido. He doesn't specify which ranks he means when he says "It is our responsibility..."
Perhaps the more experienced students among us here could offer guidance on these matters for those of us who have only started on this path recently?
Also, regarding the advice to "train harder," specifically what is meant by that? My initial banal and probably incorrect interpretation would be to train with more force, more aerobically, for more hours. I'm guessing something more (or entirely different) is implied.