Ars Magica, p 103:
"Anyone who has The Gift and a score of at least one in Magic theory may help you to perform any activity that uses your Magic Theory."
This seems to imply that if you're getting help, your assistant needs both The Gift and some Magic Theory. That makes sense.
Ars Magica, p 42 (Failed Apprentice Virtue):
"You may learn Magic Theory and serve a magus as a laboratory assistant."
This seems to imply that such a person may help in lab activities.
So which is it? Does a lab assistant need the Gift? Or is a Failed Apprentice an exception to the usual rules?
To add some more to the confusion first:
ArM5, p.105 about familiars: "They cannot, however, learn magic, although they can learn Magic Theory and serve as laboratory assistants."
What have failed apprentices and familiars in common? They are aligned with Hermetic magic, but usually do not have a complete Gift.
I would hence conclude that it is sufficient to have some affinity with Hermetic magic and knowledge of Magic Theory to be of use as a helper in the lab, and that in p. 103 the author was a little overzealous in stating the restriction.
Certainty can only be had once the issue has been errataed, though.
Berengar gave the reply that I would have given if I were more eloquent.
Presumably, a lab assistant needs the Gift (ant MT), but not the full Gift.
Can we assume then that anyone that has a supernatural talent and magic theory can work as a lab assistant? Or is a supernatural talent not enough to be considered "incompletely gifted"?
Perhaps the failed apprentice is able to help in the lab because he did so prior to the loss of his gift, and is now able to able to draw upon his experience from that time?
As for the familiar, it is connected to it's master's gift.
So, here's my suggestion for an at least internally consistent ruling:
Change the probably erroneous phrase on ArM5 p. 103: "Anyone who has The Gift and a score of at least one in Magic Theory may help ..." to "Anyone who is aligned to the Magic Realm in a way which involves Hermetic magic and has a score of at least one in Magic Theory may help ...".
The reasoning behind it is the following:
In ArM5 The Gift is a very well defined game concept. Who has it and who not can be seen from the character sheets. Completeness of the Gift is, however, not a rules concept at all, just a word in the flavor text for the Failed Apprentice Virtue. So I would have to define it clearly before using it in my rules amendment, and that is frankly too much work, and too big a risk of incompatibility with later books.
Then I do also not believe that a familar has any trace of Gift at all.
But both the familiar and the Failed Apprentice are by Hermetic magic aligned to the Magic Realm, in the sense of ArM5 p.182: the Failed Apprentice through his failed apprenticeship, the familiar through the bond.
Hence a wise woman with some supernatural Virtue inherited through her bloodline and aligned with Magic would be no help in the lab even if she learned Magic Theory 1.
But a scholar who lived at a covenant, studied Magic Theory there and got - by ArM5 p.168 - warped and aligned to the Magic Realm through exposure to Hermetic effects and the covenant Aura would become eligible as a lab helper.
I see one flaw with that view: This will lead to magi using CrVi spells to make themselves a couple of lab-assistants instead of training apprentices...
That flaw is inherent with the concept of Failed Apprentice. IOCs it has become an old chestnut to hint, how magi could make sure that those of their apprentices best at helping in the lab will become Failed Apprentices, hence cheap lab help forever.
More seriously, though: when reading ArM p.168 you will see that you need a lot of CrVi spells and cause two Minor Flaws to align somebody just by Warping to the Magic Realm. From that you can work out what the loyalty of your lab helper will be, and conclude whether you really want to entrust your projects to him.
To give someone 15 warping points?
Cast a lvl 10 CrVi spell 15 times maybe?
And this at a person with no inherant gift to start with... Anyone can be used...
75, if you wish to warp a mundane sufficiently to align him with the Magic realm via the rules from p.168.
Rather 75 times.
... and feel used ... sweet dreams for the magus.
If you raise him from birth, and warp him as a baby ...
... and then name him Igor ...
Ask yer self this: Do lab assistants actually do anything magical or do they just grind herbs, set up glasswear, keep the brazier stoked, ect.....?
If they only do grunt work it makes sense that you can use anyone for a lab asistant as long as they know magic theory. The more MT they know allows them to be more helpfull (fetching the proper components, setting up for experiments...)