Now we see that, according to the first view of approximation, the magnitudes γ_{μν}^τ’s are all small quantities of at least the first order. A glance at (46) will also show, that in this equation according to the second view of approximation, we are only to take into account those terms for which μ = ν = 4. By limiting ourselves only to terms of the lowest order we get instead of (46), first, the equations:— _d²__x__{τ}/_dt²_ = Γ₄₄^τ, where _ds_ = _dx₄_ = _dt_, or by limiting ourselves only to those terms which according to the first stand-point are approximations of the first order, $$ \frac{d^2 x_{\tau}}{dt^2} = \begin{bmatrix}44\\\tau\end{bmatrix} $$ (\tau = 1, 2, 3) $$ \frac{d^2 x_{4}}{dt^2} = - \begin{bmatrix}4^4\\4\end{bmatrix] $$ If we further assume that the gravitation-field is quasi-static, _i.e._, it is limited only to the case when the matter producing the gravitation-field is moving slowly (relative to the velocity of light) we can neglect the differentiations of the positional co-ordinates on the right-hand side with respect to time, so that we get (67) _d²__x__{τ}/_dt²_ = -½ ∂_g₄₄_/∂_x__{τ} (τ, = 1, 2, 3) This is the equation of motion of a material point according to Newton’s theory, where _g_₄₄/₂ plays the part of gravitational potential. The remarkable thing in the result is that in the first-approximation of motion of the material point, only the component _g₄₄_ of the fundamental tensor appears. Let us now turn to the field-equation (53). In this case, we have to remember that the energy-tensor of matter is exclusively defined in a narrow sense by the density ρ of matter, _i.e._, by the second member on the right-hand side of 58 [(58a, or 58b)]. If we make the necessary approximations, then all component vanish except τ₄₄ = ρ = τ. On the left-hand side of (53) the second term is an infinitesimal of the second order, so that the first leads to the following terms in the approximation, which are rather interesting for us: $$ \frac{\partial}{\partial x_{1}} \begin{bmatrix}\mu\nu\\1\end{bmatrix} + \frac{\partial}{\partial x_{2}} \begin{bmatrix}\mu\nu\\2\end{bmatrix} + \frac{\partial}{\partial x_{3}} \begin{bmatrix}\mu\nu\\3\end{bmatrix} + \frac{\partial}{\partial x_{4}} \begin{bmatrix}\mu\nu\\4\end{bmatrix} $$ By neglecting all differentiations with regard to time, this leads, when μ = ν =4, to the expression $$ - \frac{1}{2} ( \frac{\partial^2 g_{44}}{\partial x^2_{1}} + \frac{\partial^2 g_{44}}{\partial x^2_{2}} + \frac{\partial^2 g_{44}}{\partial x^2_{3}} ) = - \frac{1}{2} V^2 g_{44} $$ The last of the equations (53) thus leads to (68) ▽² _g₄₄_ = κρ. The equations (67) and (68) together, are equivalent to Newton’s law of gravitation. For the gravitation-potential we get from (67) and (68) the exp. (68a.) -κ/(8π) ∫ ρ_d_τ/_r_ whereas the Newtonian theory for the chosen unit of time gives