A classical theorem due to Young states that the cosine polynomial c n(x) = 1 + ∑k=1n cos(kx)/k is positive for all n ≥ 1 and x ∈ (0, π). We prove the following refinement. For all n ≥ 2 and x ∈ [0, π] we have 1/6 + c(π - ...