What is the indemnity principle and how is it applied in the context of a partial indemnity award?

In Lawyer's Professional Indemnity Company v. Geto [2002] O.J. No. 921 (S.C.J.) Nordheimer J. stated, at para. 16 as follows: As a further direct consequence of the application of the indemnity principle, when deciding on the appropriate hourly rates when fixing costs on a partial indemnity basis, the court should set those rates at a level that is proportionate to the actual rate being charged to the client in order to ensure that the court does not, inadvertently, fix an amount for costs that would be equivalent of costs on a substantial indemnity basis when the court is, in fact, intending to make an award on a partial indemnity basis.