Arvedui said:If I remember correctly, then Aragorn was a bit reluctant, wasn't he? At least in the beginning.
The principals advice was:
Gandalf, in Hobbiton:
Gildor:'Nine he gave to Mortal Men, proud and great, and so ensnared them. Long ago they fell under the dominion of the One, and they became Ringwraiths, shadows under his great Shadow, his most terrible servants. Long ago. It is many a year since the Nine walked abroad. Yet who knows? As the Shadow grows once more, they too may walk again.'
Tom Bombadil, at his house:{Pippin}‘Tell us about the Black Riders!’ ...
{Gildor}‘We will not speak of this here.’ ...
{Gildor}‘Has Gandalf told you nothing?’
{Frodo}‘Nothing about such creatures.’
{Gildor}‘Then I think it is not for me to say more - lest terror should keep you from your journey.' ...
{Frodo}‘I cannot imagine what information could be more terrifying than your hints and warnings!' ...
{Frodo}'I wish you would tell me plainly what the Black Riders are.'
{Gildor}‘Is it not enough to know that they are servants of the Enemy? Flee them! Speak no words to them! They are deadly. Ask no more of me! But my heart forbodes that, ere all is ended, you, Frodo son of Drogo, will know more of these fell things than Gildor Inglorion. May Elbereth protect you!’
Tom Bombadil, on the road to Bree:Tom wagged his head up and down, and there was a glint in his eyes when he heard of the Riders.
Aragorn in Bree:Out east my knowledge fails. Tom is not master of Riders from the Black Land far beyond his country.'
All the same the hobbits wished he was coming with them. They felt that he would know how to deal with Black Riders, if anyone did.
Aragorn at Weathertop:'They will return. And more are coming. There are others. I know their number. I know these Riders.' ... 'They will come on you in the wild, in some dark place where there is no help. Do you wish them to find you? They are terrible!' ... 'There! Perhaps I know more about these pursuers than you do. You fear them, but you do not fear them enough, yet.' ... 'They come from Mordor. From Mordor, Barliman, if that means anything to you.' ...
{Merry}'I don't know what came over me.'
{Aragorn}'I do. The Black Breath.'
Gandalf, in Rivendell:'For the black horses can see, and the Riders can use men and other creatures as spies, as we found at Bree. They themselves do not see the world of light as we do, but our shapes cast shadows in their minds, which only the noon sun destroys; and in the dark they perceive many signs and forms that are hidden from us: then they are most to be feared. And at all times they smell the blood of living things, desiring and hating it. Senses, too, there are other than sight or smell. We can feel their presence - it troubled our hearts, as soon as we came here, and before we saw them; they feel ours more keenly. Also, the Ring draws them.' ... 'There is little shelter or defence here, but fire shall serve for both. Sauron can put fire to his evil uses, as he can all things, but these Riders do not love it, and fear those who wield it. Fire is our friend in the wilderness.' ... 'This was the stroke of Frodo's sword. The only hurt that it did to his enemy, I fear; for it is unharmed, but all blades perish that pierce that dreadful King. More deadly to him was the name of Elbereth.'
I like Gildor's foreshadow with 'May Elbereth protect you!' But, as Frodo pointed out, there was a lot of terrible hints, but rather little substance before Aragorn spills some of the beans. Bombadil can perhaps be forgiven, as the Hobbits don't put any questions to him directly. Still, given that Frodo is the Ring Bearer, you'd think somebody could have explained to him why the Black Riders could sense the Ring!{Gandalf}'But my time is coming. The Morgul-lord and his Black Riders have come forth. War is preparing!'
{Frodo}`Then you knew of the Riders already – before I met them?'
{Gandalf}'Yes, I knew of them. Indeed I spoke of them once to you; for the Black Riders are the Ringwraiths, the Nine Servants of the Lord of the Rings. But I did not know that they had arisen again or I should have fled with you at once.'