You are right in thinking that this testimony of yours might be of benefit to Arthur, and that you ought to give it in case of extremity.

But I cannot advise you to obtrude it yet.

I understand what it would cost you, and the sacrifice you would make is too great for the doubtful good which might follow.
Neither must you trust me to act for you in this matter.

My own position is too unstable for me to be of assistance to any one.

I can sympathise with you, possibly as no one else can; but I cannot reach Arthur, either by word or by message.