Lineage is a highly important concept in traditional Japanese martial arts (budo). Its easy to presume this means the history of headmasters in a school (ryu) and certainly in the ancient (koryu) schools of Japan there are traceable lineages of headmasters going back over 20 generations in some cases. However in almost as many schools there are the formation of branch schools (ryu-ha), being departures from the mainline of the school to focus on something a bit different, or the creation of new school (ryu) entirely. Routinely in the ancient arts when certificates of mastery (e.g. menkyo kaiden, inkajo and similar) were passed from master to student it often meant that they might become a future headmaster of the school; be a kind of implicit 'I have nothing more to teach'; or 'go forth and create something of your own'. It's a process sometime refereed to as shu-ha-ri (insert link).
Aikido, its styles, its roots and practice today tell a similar story. Ueshiba, the founder of Aikido, established the Aikikai as a family based style where the school would be passed on to one in the family successively. To recognise talent (such as in the case of Koichi Tohei) people might be adopted or married into the family, and this is not unusual in many budo.
Ellis Amdur's most recent book 'Hidden in Plain Sight' (edgework.info) traces the roots of O'Sensei's power and in doing so provides a window into the lineage of the origins of Aikido. He argues that the Daito-Ryu is the creation of Sokaku Takeda from the arts his father taught him as well as others gathered from his experiences in the feudal domain. The next generation of that art included Morehei Ueshiba, who is arguably his most celebrated student, but who progressively distances himself from being his student and a licensed Daito-Ryu teacher to eventually founding aikibudo, Aikido  . Arguably one of Ueshiba (O'Sensei's) most famous students, Koichi Tohei leaves the Ueshiba legacy and family school (the Aikikai) to form his own Ki research organisation (Ki no Kenkyukai) and accompanying Shin Shin Toitsu Aikido. Finally, and a bit closer to home, Tohei's one time President and Chief instructor, Maruyama Sensei, founds Aikido Yuishinkai.
In each case the successive founder of the new school (a lineage of sorts) brings influences from outside that of his teacher, perhaps as an aid to understand the teachers art, or out of personal interest or experiences judged to be important. Personalising and owning it by incorporating these other experiences as a 'flavour' or perhaps a larger departure from that of the teacher or teachers. These experiences include other martial traditions, budo and esoteric practices. Takeda was well known for his travels to visit other dojo for lessons, and to a similar extent so was Ueshiba. Tohei cites three main teachers, while Maruyama Sensei is now tracing back to what Ueshiba experienced outside Aikido together with teachers that influenced him. Interestingly, Okajima Sensei - announced as Maruyama Sensei's successor - is well credentialled in several other arts, while Williams Sensei - Aikido Yuishinkai chief instructor - has himself studied under many acknowledged masters as well.
Lineage then might mean something beyond staying in the school and is perhaps more akin to an extension of the sempai-kohai relationship, where despite going one's own way there is respect for one's teachers.
Amdur shares that the name Daito-Ryu itself comes from a relative in the Takeda famiy who had high social standing. Ueshiba began his teaching career teaching Daito-Ryu Aiki-Jujitsu, with the name gradually changing over time as the distance from Takeda's art grew. In the process he supported his teacher financially and is said to have handed over several dojo to him as well. Tohei Sensei stayed as chief instructor of the Aikikai for a period after the founder's passing and helped spread the art to the west, before eventually resigning and starting his own organisation (a recently surfaced letter of resignation is available on the aikidojournal.com for the curious). Maruyama Sensei, when he resigned from the Ki Society, went into seclusion for 10 years - in part we suspect out of respect for his teacher and teachers organisation - before emerging to start his own organisation. Our own chief instructor has worked diligently to spread Aikido Yuishinkai internationally and Okajima Sensei has worked hard with Maruyama Sensei to bring the other budo as flavour to Aikido Yuishinkai.
Amdur shares the koan 'a shadow casts no shadow', implicitly suggesting that if a student is just a shadow or copy of their teacher, then the student of that student is unlikely to learn anything of substance (being a shadow of a shadow).
It's a big call, and troubling for hobbyist dojo like ours striving for authentic practice, whilst being mere shadows ourselves. As the incumbent next generation, many have asked can we do Tohei's or Maruyama's Aikido just by copying? For the average punter seeking modest progress the answer is probably yes, but in terms of developing the art further, looking to the past suggests that a depth of experience and quite robust martial experience outside the school is also important.
 Stan Pranin has talked about this in his audio lecture series and more recently on his blog http://blog.aikidojournal.com/2011/10/19/historic-photo-the-amazing-chameleon-photo-of-o-sensei-from-1922/)
Aikido News 2011 >