The four standards of conduct are: (a) a duty of loyalty; (b) a duty of prudence; (c) a duty to diversify investments; and (d) a duty to follow plan documents to the extent that they comply with ERISA. Congress intended to incorporate in ERISA the core principles of the common law of trusts, with modifications appropriate for employee benefit plans. ERISA's fiduciary standards are to be strictly applied bearing in mind the special nature and purpose of employee benefit plans.