Boring down the heirarchy in Rails

Wasn't aware that the following is possible:

class Account < ActiveRecord::Base
has_many :projects
end

class Project < ActiveRecord::Base
belongs_to :account
has_many :milestones
end

class Milestone < ActiveRecord::Base
belongs_to :project
end
Account.find(:first).projects.first.milestones

This gets all the milestones of the first project that belongs to the first
account.

from Rails Digest, Vol 13, Issue 424 Message 8