Based on the provided legal document, here are the key points regarding the burden of proof, formatted with the requested references:

• General Rule of Burden of Proof: The burden of proving a fact rests on the party who substantially asserts the affirmative issue, not the party who denies it; this rule may have exceptions. (!) (!) (!)
• Initial Onus: The initial onus of proof is always on the plaintiff (Section 102 of the Evidence Act). (!) (!)
• Requirement to Establish Fiduciary Relationship: Before a presumption of undue influence or a shift in burden regarding a fiduciary relationship can be drawn, the plaintiff must first establish the existence of such a relationship and the position of active confidence through pleadings and evidence. (!) (!) (!)
• Pleading vs. Evidence: Pleading is not evidence; issues are raised based on pleadings, and a failure to admit a fiduciary relationship in the written statement means the relationship itself remains an issue to be proved. (!) (!)
• Possession of Documents: Mere possession of the original sale deed by the defendant does not alter the legal position regarding the burden of proof; the plaintiff can apply for the document's production. (!)
• Distinction Between Burden and Onus: There is a distinction between the burden of proof (which generally does not shift) and the onus of proof (which shifts as evidence is presented); the right to begin follows the onus probandi. (!) (!)
• Application of Section 111: Section 111 of the Evidence Act applies to questions of good faith in transactions where one party is in a position of active confidence, but only after that relationship is established. (!) (!)
• Error in Lower Courts: The Trial Court and High Court erred in shifting the burden to the defendant without first proving the fiduciary relationship, misinterpreting Section 101 of the Evidence Act. (!) (!) (!)
• Outcome of Appeal: The impugned judgment setting aside the original issue framing is set aside, and the original issue ("Whether the sale deed... is forged and fabricated?") is revived. (!)