Mis Hurd was the one who directed my grief/sorrow/sadness and pain into writing....She was the catalyst/agent/medium/too/instrumentimplement that sent me into journalism and indirectly caused all the good thins that came after. But Miss hurd would probably deny this emphatically/clearly/definitely.
Are all the words beside and in-between slashes interchangeable? Thanks..
They don't all have exactly the same meaning- 'grief', for example, has strong associations with death, which the other two don't, though they can be used to describe the feelings after losing someone. With the last group, I would only use 'emphatically'.
"Miss Hurd was the one who directed my grief/sorrow/sadness and pain into writing....She was the catalyst/agent/medium/too/instrumentimplement that sent me into journalism and indirectly caused all the good things that came after. But Miss Hurd would probably deny this emphatically/clearly/definitely."
Well it depends on the context. Like Tdol has mentioned, grief is somehow related to death:
Grief: "Very great sadness, especially at the death of someone"
So if the writer's sadness is related to the death of someone I would consider grief to be unequaled to your other suggestions.
"A feeling of great sadness or regret"
"If you are sad, you feel unhappy, usually because something has happened that you do not like."
I wouldn't say the three are equivalent. The use of sorrow and grief implies a great sadness whereas a bare sadness has a slightly "lighter" sound to it.
In other words, I think sadness here in this context doesn't evoke a greater sadness like grief and sorrow.
As for the second group, I wouldn't they're exactly equivalent, but maybe I'm just playing with words. Here's some definitions:
"an event or person that causes great change" Stronger connotation than agent.
"a person or thing that produces a particular effect or change"
"a method or way of expressing something" I think it goes without saying that this one sticks out.
"Something that is an instrument for achieving a particular aim is used by people to achieve that aim."
Hardly as flattering as the other terms.
"a tool which works by being moved by hand or by being pulled across a surface, but which is not powered directly by electricity or fuel"
Hum... I think this one is just plain wrong here and can't even be used in this context, as opposed to the other terms.
As for the last term, I wouldn't see they are equivalent either:
Emphatically (Emphatic, adj.)
"done or said in a strong way and without any doubt"
"in a way that is easy to see, hear, read or understand"
Not as strong as emphatically I don't think.
"without any doubt"
In your excerpt, I don't think you could end the sentence with definitely.
I would say:
"But Miss Hurd would definitely deny this."
The same stands with the two other words of your last group, I would put them before the verb deny.