A catalyst accelerates rate(s) of chemical reaction(s). If you see a dilute solution of H₂O₂, you will observe slow formation of oxygen bubbles by the reaction (decomposition) of 2H₂O₂ -> 2H₂O + O₂. If you put a particle of MnO₂, the formation of bubble must become very fast. MnO₂ looks unchanged, and in a fact, you will observe no change by physical and chemical analysis. Therefore, it is speculated that just a contact between the catalyst and reactant enhances the rate of chemical reaction. However, just the presence of catalyst beside the reactant does not enhance the rate of reaction. As explained [here], the catalyst joins the reaction, and recovers its form after the reaction.

Catalysis is very complex and just like as designed wisely by nature. Both of organic and inorganic substances act, and atoms play their roles on a solid surface for catalysis. Catalysts join to chemical reactions. Catalysis is similar to the role of excellent teacher on the development of a child. An excellent teacher has deep relation with the activity of child. He/she must not be consumed like food, but can again contribute to next child. However, the teacher should not be the classroom, namely, vessel. He/she deeply relates with the child to greatly enhance the development to one certain direction, and this decides the future of child. Like this teacher, catalysts join the chemical reaction.

　触媒は化学反応を速めます．H₂O₂の薄い水溶液を見ていると，2H₂O₂ → 2H₂O + O₂の分解反応によって酸素の気泡がゆっくりと発生します．ここにMnO₂の粒子を投入すると気泡の発生は非常に速くなります．MnO₂は見たところ，また分析をしてもほとんど変化がないので，接触しただけで反応を速めたことになります．しかし，近くに存在するだけで速くなったのではありません．[ここ]に書いてあるように，触媒は化学反応に参加し，元に戻ります．

　触媒の作用は非常に巧妙で，多くの場合，有機・無機両方の物質が関与し，固体表面で原子が生き生きと活動した結果です．触媒作用は，こどもの成長に対してよい教師が果たす役割に似ています．よい教師はこどもの活動に積極的に関わり，だからといって食糧のように犠牲となるわけではなく，再び別のこどもの成長に寄与することができます．かといって，教室のように単なる入れ物ではありません．こどもと深く関わることによって特定の方向への成長を非常に速め，こどもの運命を決めています．触媒は化学反応に参加しています．