1. In the law of evidence, opinion is an inference or conclusion drawn by a witness from facts some of which are known to him and others assumed, or drawn from facts which, though lending probability to the inference, do not evolve it by a pro- cess of absolutely necessary reasoning. See Lipscomb v. State, 75 Miss. 559, 23 South. 210. An inference necessarily involving certain facts may be stated without the facts, the inference being an equivalent to a specification of the facts; but, when the facts are not necessarily involved in the inference (e. g., when the inference may be sustained upon either of several distinct phases of fact, neither of which it necessarily involves.) then the facts must be stated. Whart. Ev.